**Geospatial Analysis of Water Resources for Sustainable Agricultural Water Use in Slovenia**

Matjaž Glavan, Rozalija Cvejić, Matjaž Tratnik and Marina Pintar

Additional information is available at the end of the chapter

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## **1. Introduction**

Global population growth has greatly increased food demand. This, in turn, has intensified agricultural production, already the biggest consumer of water in the world [1]. Development of irrigation techniques has contributed to the global food production [2]. However, climate change simulations predict repeated droughts and deteriorating crop production, illustrating the critical need for sustainable irrigation [3]. Thus, a proactive water management strategy is a priority of any government in the world.

Globally, only 10% of estimated blue water (surface water, groundwater, and surface runoff) and 30% of estimated green water (evapotranspiration, soil water) resources are used for consumption. Nevertheless, water scarcity is a problem due to high variability of water resources availability in time and space [4]. Model results suggest that severe water scarcity occurs at least one month per year in almost one half of the world river basins [5]. One third of the water volume currently supplied to irrigated areas is supplied by locally stored runoff [6]. It is estimated that small reservoirs construction could increase global cereal production in low-yield regions (i.e. Africa, Asia) by approximately 35% [6]. Global water scarcity problems can now be, due to advances in hydrology science in the last decades, easily assessed on fine temporal and spatial scale [4].

Irrigation development and management in Slovenia have completely stagnated in the last decade due to financial shortages. In 1994 the Slovenian government adopted a strategy for agricultural land irrigation (i.e. National Irrigation Programme) [7]. In 1999, the World Bank

© 2013 Glavan et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Glavan et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

prepared a feasibility study of this program. However, economic constraints and lack of political will limited the implementation of the program [8].

**Water resource Data type Description/properties Data source**

Water abstraction Geo-referenced tabular data

Large water reservoirs Reservoirs Polygon layer IWRS

Reservoir characteristics Tabular data

Borehole Drilling price

Mean monthly flow m3 s-1

Soil data Polygon layer

Mean monthly specific

Surface runoff yield and

abundance

Land use Graphical Units of

runoff

Groundwater Water body Polygon layer

Accumulated surface

runoff

(m3 s-1)

Water rights Geo-referenced tabular data – water

Surface watercourse River network Polyline layer Slovenian Environmental

Available water quantities Geo-referenced tabular data - water available

River flow Geo-referenced tabular data Agency (SEA) - river flow gauging stations (m3 s-1)

for irrigation and ecologically acceptable flow

Geospatial Analysis of Water Resources for Sustainable Agricultural Water Use in Slovenia


Hydrogeology, water availability

water in groundwater body

Runoff Raster layers (mm year-1) SEA

hydrological group)

Curve number Share of precipitation as surface runoff defined

Irrigation norm Gross irrigation norm in millimetres, litres or m3

Hydro-module Qualities of water used in litres per second per

Polygon layer

representation

Irrigation Irrigation area Polygon layer UL-BF

Irrigation systems Polygon layer

Agricultural Land - GERK

**Table 1.** Input data sources for water resources availability assessment

abstraction (m3 s-1) and % of all estimated

Soil properties (texture, horizons, bedrock, hydraulic conductivity, soil water capacity,

by land use and soil hydrological group, slope

DEM Raster layer - Digital elevation model - 25m The Surveying and Mapping

of water per hectare for defined crop and soils in one year for optimal growing conditions

hectare of crop in one irrigation cycle

Total area and actually irrigated land

Land cover classification and spatial

Quantity of water in millimetres and m3 ha-1 IWRS

l s-1 km2 IWRS

Institute of Water of the Republic of Slovenia (IWRS)

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201

Slovenian National Committee on Large Dams (SNCLD),

Geological Survey of Slovenia

University of Ljubljana - Biotechnical Faculty (UL-BF)

Authority of the Republic of Slovenia (SMARS)

Statistical Office of Slovenia

Ministry of Agriculture and the Environment of the Republic of

Slovenia (MAERS)

SEA

(GSS)

SEA, GSS

UL-BF

IWRS, UL-BF

UL-BF

(SOS)

Slovenia is experiencing periodic droughts of varying intensities in different parts of the country. According to the Court of Audit, the total costs in the agricultural sector due to the droughts in 2000, 2001, 2003 and 2006 were 247 million euro (EUR) [9]. During the same period the government spent 85.9 million EUR for the elimination of the consequen‐ ces of droughts, and only 3.3 million € on drought prevention measures. This figure is particularly worrisome, because Slovenia is relatively rich in water, with 800-3,000 mm of precipitation per year. With appropriate technical measures, water could be redistributed temporally and spatially, limiting water scarcity and drought effects. Recurring droughts and the results of global and regional climate scenarios [10] predict a tightening of crop production conditions in Slovenia, illustrating the urgent need to address the availability of water resources [11-17].

The Ministry of Agriculture and the Environment has identified the current lack of irrigation infrastructure as a serious obstacle to prevention of agricultural damage and improvement of crop production. Therefore, the Ministry called for two research projects of the Target Research Program, as preparation for the establishment of a new Irrigation Strategy. The first project, Water Perspectives of Slovenia and the Possibility of Water Use in Agriculture (V4-0487) [9, 18], had two objectives, (a) to determine the current water quantity of Slovenian water resources (ground and surface waters, wastewater and sewage treatment plants discharges, existing large reservoirs) potentially available for use, with emphasis on irrigation and (b) to determine the extent to which these water resource meet current irrigation needs.

In 2012 the second project, Projections of Water Quantities for Irrigation in Slovenia (V4-1066) was completed, with the objective to determine to what extent the surface runoff water retained in small water reservoirs along with the rest of the available water, from other water resources, covers irrigation needs. The project also took into account the irrigation norms for different crops, soils, climate zones and climate change scenarios [19]. Analyses of the available water quantities, potential irrigation areas, technical possibilities of construction of small reservoirs, legislation, irrigation norms for crops, climate change impacts were made as part of the agricultural drought risk assessment.

The purpose of this chapter is to present a novel and globally applicable approach for identification of agricultural lands that are at risk for drought. Spatial analysis of availa‐ ble water resources and their quantities for the sustainable irrigation of agricultural land is the key to an efficient integrated water management strategy. Knowing the spatial distribution, accessibility, abundance and availability of water resources is an important element of national security, with regards to the production of sufficient quantities of quality food. Assessing water resources is especially critical in the light of empirical meteorological data and climate model results showing clear changes in the allocation of precipitation and in seasonal patterns.


**Table 1.** Input data sources for water resources availability assessment

prepared a feasibility study of this program. However, economic constraints and lack of

Slovenia is experiencing periodic droughts of varying intensities in different parts of the country. According to the Court of Audit, the total costs in the agricultural sector due to the droughts in 2000, 2001, 2003 and 2006 were 247 million euro (EUR) [9]. During the same period the government spent 85.9 million EUR for the elimination of the consequen‐ ces of droughts, and only 3.3 million € on drought prevention measures. This figure is particularly worrisome, because Slovenia is relatively rich in water, with 800-3,000 mm of precipitation per year. With appropriate technical measures, water could be redistributed temporally and spatially, limiting water scarcity and drought effects. Recurring droughts and the results of global and regional climate scenarios [10] predict a tightening of crop production conditions in Slovenia, illustrating the urgent need to address the availability

The Ministry of Agriculture and the Environment has identified the current lack of irrigation infrastructure as a serious obstacle to prevention of agricultural damage and improvement of crop production. Therefore, the Ministry called for two research projects of the Target Research Program, as preparation for the establishment of a new Irrigation Strategy. The first project, Water Perspectives of Slovenia and the Possibility of Water Use in Agriculture (V4-0487) [9, 18], had two objectives, (a) to determine the current water quantity of Slovenian water resources (ground and surface waters, wastewater and sewage treatment plants discharges, existing large reservoirs) potentially available for use, with emphasis on irrigation and (b) to determine the extent to which these water resource meet

In 2012 the second project, Projections of Water Quantities for Irrigation in Slovenia (V4-1066) was completed, with the objective to determine to what extent the surface runoff water retained in small water reservoirs along with the rest of the available water, from other water resources, covers irrigation needs. The project also took into account the irrigation norms for different crops, soils, climate zones and climate change scenarios [19]. Analyses of the available water quantities, potential irrigation areas, technical possibilities of construction of small reservoirs, legislation, irrigation norms for crops, climate change impacts were made as part of the

The purpose of this chapter is to present a novel and globally applicable approach for identification of agricultural lands that are at risk for drought. Spatial analysis of availa‐ ble water resources and their quantities for the sustainable irrigation of agricultural land is the key to an efficient integrated water management strategy. Knowing the spatial distribution, accessibility, abundance and availability of water resources is an important element of national security, with regards to the production of sufficient quantities of quality food. Assessing water resources is especially critical in the light of empirical meteorological data and climate model results showing clear changes in the allocation of

political will limited the implementation of the program [8].

200 Current Perspectives in Contaminant Hydrology and Water Resources Sustainability

of water resources [11-17].

current irrigation needs.

agricultural drought risk assessment.

precipitation and in seasonal patterns.

## **2. Materials and methods**

## **2.1. Input data**

Table 1 provides an overview of the data used for spatial analysis (data type, name, source location, description). If certain type of map was not available we created maps from tabular data provided from different sources. This type of spatial analysis requires a wide range of data starting with land use classes and soil types and their position in space as these have primary impact on surface runoff, percolation of water to groundwater and on soil water content.

was installed within the project: Adapting technology of production to climatic conditions for achieving high quality yield of olives and olive oil (V4-0557). There are several reasons for the absence of olive grove irrigation in Slovenia: relatively high annual precipitation, grower's belief in the relatively low sensitivity of olives trees to drought, lack of reliable water sources, and the terrain, which makes installation of irrigation equipment expensive. Plantations of forest trees with fast growing species like poplar are usually situated on agricultural land. The reasons for growing forest trees on agricultural land are different (paper industry, hydromeliorations, land reclamations, ameliorations). However, after harvesting these areas could be allocated for agricultural production. Their suitability is even greater because these areas are usually near water resources. Uncultivated agricultural land is usually excluded from production, due to different types of construction sites, only for a certain time period. After completion of works these areas in the majority of cases return back to agricultural production.

Geospatial Analysis of Water Resources for Sustainable Agricultural Water Use in Slovenia

**Area**

**agricultural land**

**Percent (%) of Slovenia**

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203

**Hectare (ha) Percent (%) of**

Fields and gardens 182,146.76 82.29 8.98

Hops 1,977.91 0.89 0.10

Permanent crops on fields 335.95 0.15 0.02

Greenhouses 130.01 0.06 0.01

Nurseries 47.84 0.02 0.00

Intensive orchards 4,385.30 1.98 0.22

Extensive orchards 23,929.25 10.81 1.18

Olive groves 1,810.83 0.82 0.09

Other permanent crops 416.53 0.19 0.02

Plantations of forest trees 271.39 0.12 0.01

Uncultivated agricultural land 5,903.37 2.67 0.29

Total 221,355.15 100.00 10.92

**Table 2.** Agricultural land potentially suitable for irrigation in Slovenia

**Agricultural land use classes**

Input data also includes river network, river flow, water abstraction and available water quantities for irrigation and ecologically acceptable flow to represent surface watercourses. Additional inputs include data on reservoir characteristics for spatial representation of large water reservoirs. Groundwater data includes hydrogeology and water availability layers, borehole drilling prices and water rights. The widest range of data was needed to spatially represent accumulated surface runoff. We included in the analysis runoff, mean monthly flow, mean monthly specific runoff, soil data, curve number and irrigation areas and norms which resulted in surface runoff yield and water abundance calculations. Geographic Information System ArcGIS software version 9.3 was used for all spatial analyses. Due to the characteristics of the spatial analysis with the raster layers (raster cells) we used extension build in the ArcGIS program toolbox called Spatial Analyst Tool.

## **2.2. Study area agricultural land**

The case study area is the Republic of Slovenia (2,020,318 ha), situated in central Europe between Italy, Austria, Hungary and Croatia. A land use analysis showed that agricultural land potentially suitable for irrigation covers 221,355 ha or 10.3 % (Figure 1, Table 2) of the country.

Based on a land use map, the following agricultural land use classes [20] were identified as suitable for irrigation:


Fields and gardens are the most suitable areas for irrigation, especially when crop production is being intensified. Irrigation in areas planted with hops, permanent crops on fields (aspara‐ gus, artichokes, rhubarb, etc.), intensive orchards (apple trees, pear trees, etc.), nurseries (fruit trees, vines, olive trees, etc.,) and in greenhouses, is particularly critical for sustainable crop production. Extensive orchards are potential areas where new intensive fruit plantations could be planted or old extensive orchards renewed, both could be irrigated to secure more reliable yield. Olive groves are not generally irrigated in Slovenia. An experimental irrigation system was installed within the project: Adapting technology of production to climatic conditions for achieving high quality yield of olives and olive oil (V4-0557). There are several reasons for the absence of olive grove irrigation in Slovenia: relatively high annual precipitation, grower's belief in the relatively low sensitivity of olives trees to drought, lack of reliable water sources, and the terrain, which makes installation of irrigation equipment expensive. Plantations of forest trees with fast growing species like poplar are usually situated on agricultural land. The reasons for growing forest trees on agricultural land are different (paper industry, hydromeliorations, land reclamations, ameliorations). However, after harvesting these areas could be allocated for agricultural production. Their suitability is even greater because these areas are usually near water resources. Uncultivated agricultural land is usually excluded from production, due to different types of construction sites, only for a certain time period. After completion of works these areas in the majority of cases return back to agricultural production.

**2. Materials and methods**

202 Current Perspectives in Contaminant Hydrology and Water Resources Sustainability

program toolbox called Spatial Analyst Tool.

**2.2. Study area agricultural land**

Table 1 provides an overview of the data used for spatial analysis (data type, name, source location, description). If certain type of map was not available we created maps from tabular data provided from different sources. This type of spatial analysis requires a wide range of data starting with land use classes and soil types and their position in space as these have primary impact on surface runoff, percolation of water to groundwater and on soil water

Input data also includes river network, river flow, water abstraction and available water quantities for irrigation and ecologically acceptable flow to represent surface watercourses. Additional inputs include data on reservoir characteristics for spatial representation of large water reservoirs. Groundwater data includes hydrogeology and water availability layers, borehole drilling prices and water rights. The widest range of data was needed to spatially represent accumulated surface runoff. We included in the analysis runoff, mean monthly flow, mean monthly specific runoff, soil data, curve number and irrigation areas and norms which resulted in surface runoff yield and water abundance calculations. Geographic Information System ArcGIS software version 9.3 was used for all spatial analyses. Due to the characteristics of the spatial analysis with the raster layers (raster cells) we used extension build in the ArcGIS

The case study area is the Republic of Slovenia (2,020,318 ha), situated in central Europe between Italy, Austria, Hungary and Croatia. A land use analysis showed that agricultural land potentially suitable for irrigation covers 221,355 ha or 10.3 % (Figure 1, Table 2) of the

Based on a land use map, the following agricultural land use classes [20] were identified as

**a.** fields and gardens, hops plantations, permanent crops on fields, greenhouses, nurseries,

Fields and gardens are the most suitable areas for irrigation, especially when crop production is being intensified. Irrigation in areas planted with hops, permanent crops on fields (aspara‐ gus, artichokes, rhubarb, etc.), intensive orchards (apple trees, pear trees, etc.), nurseries (fruit trees, vines, olive trees, etc.,) and in greenhouses, is particularly critical for sustainable crop production. Extensive orchards are potential areas where new intensive fruit plantations could be planted or old extensive orchards renewed, both could be irrigated to secure more reliable yield. Olive groves are not generally irrigated in Slovenia. An experimental irrigation system

intensive orchards, extensive orchards, other permanent crops,

**c.** plantations of forest trees, uncultivated agricultural land.

**2.1. Input data**

content.

country.

suitable for irrigation:

**b.** olive groves,


**Table 2.** Agricultural land potentially suitable for irrigation in Slovenia

**Figure 1.** Geographic location of Slovenia, agricultural land potentially suitable for irrigation and locations of irriga‐ tion systems

**Figure 2.** Water accessibility classes for water reservoir in Slovenia

Geospatial Analysis of Water Resources for Sustainable Agricultural Water Use in Slovenia

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205

**Figure 3.** Water accessibility classes for surface watercourses in Slovenia

In Slovenia in 2010, of 8,299 ha was prepared for irrigation and, only 3,851 ha was actually irrigated [21], accounting for less than 4 % and 2 % of total agricultural land potentially suitable for irrigation (221,355 ha), respectively (Table 3).


**Table 3.** Total area (ha) of agricultural land prepared for irrigation and actually irrigated in Slovenia

#### **2.3. Surface watercourses and large water reservoirs**

Water accessibility classes for surface watercourses or water reservoirs were spatially defined and created from the percentage (%) of defined agricultural land use areas suitable for irrigation (Figure 2 and 3). The project on water perspectives (V4-0487) [8, 18] defined the percentage of area that can be directly irrigated from existing water reservoirs. Dry water reservoirs were excluded from the analysis. The analysis was supported with field work (questionnaires) checking the status and operational management of reservoirs and with analysis of regulations on operation and maintenance of reservoirs.

Geospatial Analysis of Water Resources for Sustainable Agricultural Water Use in Slovenia http://dx.doi.org/10.5772/53528 205

**Figure 2.** Water accessibility classes for water reservoir in Slovenia

**Figure 1.** Geographic location of Slovenia, agricultural land potentially suitable for irrigation and locations of irriga‐

In Slovenia in 2010, of 8,299 ha was prepared for irrigation and, only 3,851 ha was actually irrigated [21], accounting for less than 4 % and 2 % of total agricultural land potentially suitable

Land prepared for irrigation (ha) 6,339 5,303 4,727 5,395 7,876 7,732 7,841 7,604 8,299 Actually irrigated land (ha) 2,741 2,329 1,812 2,837 3,759 3,651 3,732 3,501 3,851

Water accessibility classes for surface watercourses or water reservoirs were spatially defined and created from the percentage (%) of defined agricultural land use areas suitable for irrigation (Figure 2 and 3). The project on water perspectives (V4-0487) [8, 18] defined the percentage of area that can be directly irrigated from existing water reservoirs. Dry water reservoirs were excluded from the analysis. The analysis was supported with field work (questionnaires) checking the status and operational management of reservoirs and with

**Table 3.** Total area (ha) of agricultural land prepared for irrigation and actually irrigated in Slovenia

analysis of regulations on operation and maintenance of reservoirs.

**Year 2003 2004 2005 2006 2007 2008 2009 2010 2011**

tion systems

for irrigation (221,355 ha), respectively (Table 3).

204 Current Perspectives in Contaminant Hydrology and Water Resources Sustainability

**2.3. Surface watercourses and large water reservoirs**

**Figure 3.** Water accessibility classes for surface watercourses in Slovenia

The project identified eighteen (18) water reservoirs, from which at least part of the accumu‐ lated water could be allocated for irrigation of agricultural land. In all of the large water reservoirs impact areas were determined, where water quantities are sufficient for direct irrigation of at least 30 % of the agricultural land potentially suitable for irrigation (Figure 2). It follows that the use of water from certain water reservoirs is quantitatively limited to water available for irrigation of agricultural land.

linkedwiththreeclassesofaveragecostforborehole(well)drilling.Theareaswitheasilyaccessible groundwater and the lowest price for borehole drilling were attributed with 100% availability of water (Table 4). The other two accessibility classes have smaller or higher number of percentag‐ es (Figure 4), in proportion to the price of borehole drilling and the accessibility of groundwater.

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207

It is important to note that groundwater is priority reserved for drinking water. A relatively small percentage of groundwater is actually abstracted; with the highest rate (35%) in the Savska kotlina with Ljubljansko barje in central Slovenia. However, the analysis of the officially assigned abstraction rates from granted water rights showed that three groundwater bodies are 100% utilized (Savska kotlina with Ljubljansko barje. Kamniško-Savinjske Alpe in central

The average price for borehole drilling in 2010 in an area with easily accessible groundwa‐ ter (diameter 100 mm, the average rate of flow of 5.5 l s-1, depth 50 m) was estimated to be 11,000 EUR. The average price for borehole drilling in an area with medium accessi‐ ble groundwater (diameter 100 mm, yield up to 5.5 l s-1, depth of 70 m to 150 m) was estimated to be 15,000 and 30,000 EUR. The average price for borehole drilling in areas with hard accessible groundwater (diameter 100 mm, the average yield of 1 l s-1, at least 200 m depth) was estimated to be 44,300 EUR. Accessibility of groundwater and price of borehole drilling is highly dependent on geology, groundwater levels, aquifer layer

Slovenia and Vzhodne Slovenske gorice in eastern Slovenia).

**Figure 4.** Water accessibility classes for groundwater in Slovenia

thickness and type of aquifer.

The percentage (%) of the area that can be directly irrigated from surface watercourses was determined on the basis of the available water quantity for irrigation at the last point down‐ stream of individual surface watercourse water body. The project defined seventy (70) areas suitable for irrigation (Figure 3).

Area determination followed the criteria [18] below:


Water accessibility points for water reservoirs and watercourses were determined by the extent of agricultural land (ha, %), which may be irrigated with the water assigned for the agricultural use from both sources. It is important that the use of water from a reservoir is quantitatively limited to the water available for agricultural land irrigation, and water from watercourses is limited to ecologically acceptable flows.

Largewaterreservoirsandsurfacewatersareattributedwith100pointsofavailabilityifthewater resourcesuppliessufficientquantitiesofwaterforirrigationofallpotentiallysuitableagricultur‐ al land for irrigation in the defined area of the water body (Table 4). If water quantities are insufficient (0 to 99%) for irrigation of a whole defined area of water body adequate for irriga‐ tion, the water resource is attributed with availability points between 0 and 99.

#### **2.4. Groundwater**

Water accessibility classes for groundwater were determined based on a hydrogeological map [22]whichdefinesthreeclassesofgroundwateravailability(hard,mediumandeasy)whichwere linkedwiththreeclassesofaveragecostforborehole(well)drilling.Theareaswitheasilyaccessible groundwater and the lowest price for borehole drilling were attributed with 100% availability of water (Table 4). The other two accessibility classes have smaller or higher number of percentag‐ es (Figure 4), in proportion to the price of borehole drilling and the accessibility of groundwater.

It is important to note that groundwater is priority reserved for drinking water. A relatively small percentage of groundwater is actually abstracted; with the highest rate (35%) in the Savska kotlina with Ljubljansko barje in central Slovenia. However, the analysis of the officially assigned abstraction rates from granted water rights showed that three groundwater bodies are 100% utilized (Savska kotlina with Ljubljansko barje. Kamniško-Savinjske Alpe in central Slovenia and Vzhodne Slovenske gorice in eastern Slovenia).

**Figure 4.** Water accessibility classes for groundwater in Slovenia

The project identified eighteen (18) water reservoirs, from which at least part of the accumu‐ lated water could be allocated for irrigation of agricultural land. In all of the large water reservoirs impact areas were determined, where water quantities are sufficient for direct irrigation of at least 30 % of the agricultural land potentially suitable for irrigation (Figure 2). It follows that the use of water from certain water reservoirs is quantitatively limited to water

The percentage (%) of the area that can be directly irrigated from surface watercourses was determined on the basis of the available water quantity for irrigation at the last point down‐ stream of individual surface watercourse water body. The project defined seventy (70) areas

**•** water abstraction within each catchment area must not be greater than the available water quantity at the last point downstream of individual catchment area of surface watercourse

**•** total water abstraction within a system of catchment areas must not be greater than the total capacity of a set of catchment areas, which is the same size as the availability of water

**•** irrigation area of each watercourse is located in the catchment area of the surface water‐

**•** horizontal distance from the river to the border of agricultural land area potentially suitable

**•** difference in height between the watercourse and agricultural land suitable for irrigation

Water accessibility points for water reservoirs and watercourses were determined by the extent of agricultural land (ha, %), which may be irrigated with the water assigned for the agricultural use from both sources. It is important that the use of water from a reservoir is quantitatively limited to the water available for agricultural land irrigation, and water from watercourses is

Largewaterreservoirsandsurfacewatersareattributedwith100pointsofavailabilityifthewater resourcesuppliessufficientquantitiesofwaterforirrigationofallpotentiallysuitableagricultur‐ al land for irrigation in the defined area of the water body (Table 4). If water quantities are insufficient (0 to 99%) for irrigation of a whole defined area of water body adequate for irriga‐

Water accessibility classes for groundwater were determined based on a hydrogeological map [22]whichdefinesthreeclassesofgroundwateravailability(hard,mediumandeasy)whichwere

tion, the water resource is attributed with availability points between 0 and 99.

quantity in the final (outflow) node of the concerned system of catchment areas;

**•** maintenance of ecologically acceptable flow (Official Gazette RS, No. 97/2009),

available for irrigation of agricultural land.

course water body (some exceptions);

limited to ecologically acceptable flows.

does not exceed 100 m.

**2.4. Groundwater**

for irrigation is not greater than 3 km (some exceptions);

Area determination followed the criteria [18] below:

206 Current Perspectives in Contaminant Hydrology and Water Resources Sustainability

suitable for irrigation (Figure 3).

water body,

The average price for borehole drilling in 2010 in an area with easily accessible groundwa‐ ter (diameter 100 mm, the average rate of flow of 5.5 l s-1, depth 50 m) was estimated to be 11,000 EUR. The average price for borehole drilling in an area with medium accessi‐ ble groundwater (diameter 100 mm, yield up to 5.5 l s-1, depth of 70 m to 150 m) was estimated to be 15,000 and 30,000 EUR. The average price for borehole drilling in areas with hard accessible groundwater (diameter 100 mm, the average yield of 1 l s-1, at least 200 m depth) was estimated to be 44,300 EUR. Accessibility of groundwater and price of borehole drilling is highly dependent on geology, groundwater levels, aquifer layer thickness and type of aquifer.


quantity of water available for irrigation (Table 4 and 5) [6, 23]. The definition was also based on the optimum volume of a small reservoir for the irrigation of one hectare (of accumulated surface runoff) defined by agro-meteorological stations in different irrigation areas for a dry year with a five-year return period (Table 4). Classes of potential winter yield of surface runoff (mm) (1971 - 2000) (Figure 5) were merged with a map of irrigation areas creating classes with

**Groups of crops**

Geospatial Analysis of Water Resources for Sustainable Agricultural Water Use in Slovenia

 531,8 968,2 strawberries 878 25 692,4 1307,6 vegetables – low norm 1292 50 1477,4 3022,6 vegetables – high norm 2871 75 1941,2 4058,8 permanent crops 3720 100

 219,5 1280,5 strawberries 1125 25 284,2 1715,8 vegetables – low norm 1625 50 536,7 3463,3 vegetables – high norm 3097 75 598,9 3901,1 permanent crops 3482 100

 131,1 868,9 strawberries 588 25 187,3 1312,7 vegetables – low norm 1031 50 296,8 2203,2 vegetables – high norm 2271 75 350,7 2649,3 permanent crops 2359 100

 168,4 831,6 strawberries 951 25 241,0 1259,0 vegetables – low norm 1299 50 452,1 2547,9 vegetables – high norm 2568 75 521,3 2978,7 permanent crops 3024 100

500 45,0 455,0 / / 25

1500 115,3 1384,7 vegetables – high norm 1697 75 2500 182,3 2317,7 permanent crops 2157 100

MED – Mediterranean irrigation area; PAN – Pannonian irrigation area; SMED – Sub-Mediterranean irrigation area; SPAN – Sub-Pannonian irrigation area; CENT – Central Slovenian irrigation area; ALPE – Alpine-Dinaric irrigation area

**Table 5.** Determination of availability points for accumulated surface runoff water in small water reservoirs based on average available water for irrigation in reservoir and maximal irrigation norm for drip irrigation and light soils

The magnitude of the abundance points was based on the maximum irrigation norm (drip irrigation) for one hectare of permanent crops (orchards) on light soils and its corresponding optimal reservoir volume for irrigation. If there was enough water for the irrigation of this type of crop (orchard, light soils, drip irrigation, maximum irrigation norm) in an irrigation area it was given 100 availability points (Table 4). Each subsequent class was determined by

vegetables – low norm

**Maximal irrigation norm (m3)**

> 552 848

**Water availability points**

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209

50

assigned attributed points of surface runoff yield abundance [24].

**Average available for irrigation**

1000 80,8 919,2 strawberries

**Volume of reservoir (m3)**

**loss**

**Optimal Average**

**Irrigation area**

**MED**

**PAN**

**SMED**

**SPAN**

**CENT**

**Surface runoff as small water reservoirs** - customized to winter yield, maximal irrigation norm, light soils and drip irrigation


MED – Mediterranean irrigation area; PAN – Pannonian irrigation area; SMED – Sub-Mediterranean irrigation area; SPAN – Sub-Pannonian irrigation area; CENT – Central Slovenian irrigation area; ALPE – Alpine-Dinaric irrigation area

1 irrigation of x% of area identified as suitable for irrigation from large water reservoir and surface watercourses

*<sup>2</sup>* class of winter yield abundance does not exist for certain irrigation area

*<sup>3</sup>* winter yield abundance of surface runoff from 1 ha of land is sufficient for irrigation of 1 ha of permanent crop (orchard)

**Table 4.** Determination of potential availability of water resources for irrigation based on water direct accessibility from (1) water reservoirs, (2) surface watercourses, (3) groundwater and (4) abundance of surface runoff yield as small water reservoirs

Areaswitheasilyaccessiblegroundwaterandthereforewiththelowestpriceofboreholedrilling are attributed with 100 points of availability (Table 4). Medium and hard accessible groundwa‐ ter areas are attributed with 50 and 25 availability points, respectively. The price of borehole drilling for those two classes is two or four times higher than for easily accessible groundwater.

#### **2.5. Accumulated surface runoff**

To create classes of potential abundance of surface runoff for accumulation in small reservoirs, we had to gather information on the maximum irrigation norm for drip irrigation on light soils for several groups of plants per one hectare (vegetables - low norm, vegetables – high norm, strawberries and permanent crops). This was for all irrigation areas and based on the average quantity of water available for irrigation (Table 4 and 5) [6, 23]. The definition was also based on the optimum volume of a small reservoir for the irrigation of one hectare (of accumulated surface runoff) defined by agro-meteorological stations in different irrigation areas for a dry year with a five-year return period (Table 4). Classes of potential winter yield of surface runoff (mm) (1971 - 2000) (Figure 5) were merged with a map of irrigation areas creating classes with assigned attributed points of surface runoff yield abundance [24].

**Water resource**

irrigation

water reservoirs

**2.5. Accumulated surface runoff**

**Large water reservoirs**

**Surface watercourses (rivers, streams)**

**Water accessibility and abundance**

208 Current Perspectives in Contaminant Hydrology and Water Resources Sustainability

**Groundwater** - customized to geology and borehole drilling costs

unrestricted (irrigation of 100% of area*<sup>1</sup>*) 100 restricted (irrigation of 0 to 99% of area) 0-99

unrestricted (irrigation of 100% of area) 100 restricted (irrigation of 0 to 99% of area) 0-99

> abundance (m3 ha-1)

**No accessible water resource** 0

*<sup>2</sup>* class of winter yield abundance does not exist for certain irrigation area

**Surface runoff as small water reservoirs** - customized to winter yield, maximal irrigation norm, light soils and drip

1 MED

MED – Mediterranean irrigation area; PAN – Pannonian irrigation area; SMED – Sub-Mediterranean irrigation area; SPAN – Sub-Pannonian irrigation area; CENT – Central Slovenian irrigation area; ALPE – Alpine-Dinaric irrigation area 1 irrigation of x% of area identified as suitable for irrigation from large water reservoir and surface watercourses

*<sup>3</sup>* winter yield abundance of surface runoff from 1 ha of land is sufficient for irrigation of 1 ha of permanent crop (orchard)

Areaswitheasilyaccessiblegroundwaterandthereforewiththelowestpriceofboreholedrilling are attributed with 100 points of availability (Table 4). Medium and hard accessible groundwa‐ ter areas are attributed with 50 and 25 availability points, respectively. The price of borehole drilling for those two classes is two or four times higher than for easily accessible groundwater.

To create classes of potential abundance of surface runoff for accumulation in small reservoirs, we had to gather information on the maximum irrigation norm for drip irrigation on light soils for several groups of plants per one hectare (vegetables - low norm, vegetables – high norm, strawberries and permanent crops). This was for all irrigation areas and based on the average

**Table 4.** Determination of potential availability of water resources for irrigation based on water direct accessibility from (1) water reservoirs, (2) surface watercourses, (3) groundwater and (4) abundance of surface runoff yield as small

easy 100 medium 50 hard 25

> 2 PAN

Relative slope < 6 % 0 0 0 0 0 0

3 SMED

> 6000 - *<sup>2</sup>* - 100 *<sup>3</sup>* - 100 100 4000-6000 75 - 100 100 100 100 2000-4000 50 75 75 75 100 100 1000-2000 25 50 50 50 75 100 500-1000 25 25 25 25 50 100 < 500 25 25 - 25 - -

4 SPAN

5 CENT

6 ALPS

**Water availability points**


MED – Mediterranean irrigation area; PAN – Pannonian irrigation area; SMED – Sub-Mediterranean irrigation area; SPAN – Sub-Pannonian irrigation area; CENT – Central Slovenian irrigation area; ALPE – Alpine-Dinaric irrigation area

**Table 5.** Determination of availability points for accumulated surface runoff water in small water reservoirs based on average available water for irrigation in reservoir and maximal irrigation norm for drip irrigation and light soils

The magnitude of the abundance points was based on the maximum irrigation norm (drip irrigation) for one hectare of permanent crops (orchards) on light soils and its corresponding optimal reservoir volume for irrigation. If there was enough water for the irrigation of this type of crop (orchard, light soils, drip irrigation, maximum irrigation norm) in an irrigation area it was given 100 availability points (Table 4). Each subsequent class was determined by 25 availability points less, as it does not facilitate sufficient quantities of surface runoff water for irrigation of all groups of agricultural plants.

The final product of assembly and reclassification of individual data resulted in a map of abundance classes of potential surface runoff yield for the dry winter period and irrigation norm by irrigation areas (Figure 6). Also excluded from further analysis was data with a relative slope of less than 6%, and undefined areas (urban, rocky, surface waters). These areas

Geospatial Analysis of Water Resources for Sustainable Agricultural Water Use in Slovenia

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211

**Figure 6.** Water abundance classes for potential surface runoff yield for dry winter period in Slovenia

The determination of drought risk classes of agricultural land suitable for irrigation is the sum of the attributed availability points of each individual water resource suitable for irrigation of agricultural land (Table 6). Water resources (large water reservoirs, surface watercourses, groundwater and surface runoff yield) are spatially defined and interrelated (Figures 2 - 6). The analysis was conducted with raster layers whose spatial resolution was 100×100 m (1 ha)

Drought risk assessment for agricultural land suitable for irrigation is divided into 6 classes (Table 6). Class 1 is attributed with zero points and indicates areas with potential absence of available water resources for irrigation and is defined as an area with 'distinct drought risk'. Class 6 is attributed with 400 availability points, as all water resources (included in the research) are potentiality available for irrigation and is defined as area with virtually no drought risk if proper measures are undertaken. Intermediate classes between 2 and 5 have

were attributed with 0 availability points.

**2.6. Drought risk classes definition**

for the entire study area.

The determination of abundance points in the case of irrigated land for the Mediterranean and central Slovenian irrigation areas was as follows.

For the drip irrigation of one hectare of permanent crop with maximum irrigation norm on light soils (3,720 m3 ha-1 per year) and water balance for a dry year with a five-year return period we need a small reservoir with optimal volume of 6,000 m3 of water (Table 5). This means that in the Mediterranean area, where potential accumulated surface runoff yield is more than 6,000 m3 ha-1, it is possible to irrigate most of the crops. Therefore this abundance class was attributed with 100 availability points (Table 4). If it is possible to accumulate only up to 1000 m³ ha-1 of surface runoff yield in the Mediterranean irrigation area in 'dry year with five-year return period', then only a small share of crops can be irrigated. This means that the water quantity is insufficient to meet the water needs of the majority of crops in this area. Irrigation of strawberries in the Mediterranean area requires 1,500 m3 of water. Accordingly, this abundance class was attributed with 25 availability points (Table 4 and 5). In central Slovenia, for the drip irrigation of one hectare of permanent crop with maximum irrigation norm on light soil, 2,157 m3 ha-1 per year of water (dry year with five-year return period) is needed. If we include the water balance of the area, a small reservoir with volume of 2,500 m3 would be needed. This means that in central Slovenia where potentially accumulated surface runoff yield exceeds 2,000 m3 ha, the abundance classes were attributed with 100 availability points (Table 4 and 5).

**Figure 5.** Potential surface runoff yield (mm) for dry winter period with five year return period in Slovenia

The final product of assembly and reclassification of individual data resulted in a map of abundance classes of potential surface runoff yield for the dry winter period and irrigation norm by irrigation areas (Figure 6). Also excluded from further analysis was data with a relative slope of less than 6%, and undefined areas (urban, rocky, surface waters). These areas were attributed with 0 availability points.

**Figure 6.** Water abundance classes for potential surface runoff yield for dry winter period in Slovenia

## **2.6. Drought risk classes definition**

25 availability points less, as it does not facilitate sufficient quantities of surface runoff water

The determination of abundance points in the case of irrigated land for the Mediterranean and

For the drip irrigation of one hectare of permanent crop with maximum irrigation norm on light

it is possible to irrigate most of the crops. Therefore this abundance class was attributed with 100 availability points (Table 4). If it is possible to accumulate only up to 1000 m³ ha-1 of surface runoff yield in the Mediterranean irrigation area in 'dry year with five-year return period', then only a small share of crops can be irrigated. This means that the water quantity is insufficient to meet the water needs of the majority of crops in this area. Irrigation of strawberries in the Mediterranean area requires 1,500 m3 of water. Accordingly, this abundance class was attributed with 25 availability points (Table 4 and 5). In central Slovenia, for the drip irrigation of one hectare of

year with five-year return period) is needed. If we include the water balance of the area, a small

**Figure 5.** Potential surface runoff yield (mm) for dry winter period with five year return period in Slovenia

Mediterranean area, where potential accumulated surface runoff yield is more than 6,000 m3

ha-1 per year) and water balance for a dry year with a five-year return period we

of water (Table 5). This means that in the

would be needed. This means that in central Slovenia where

ha-1 per year of water (dry

ha, the abundance classes were

ha-1,

for irrigation of all groups of agricultural plants.

210 Current Perspectives in Contaminant Hydrology and Water Resources Sustainability

central Slovenian irrigation areas was as follows.

reservoir with volume of 2,500 m3

need a small reservoir with optimal volume of 6,000 m3

permanent crop with maximum irrigation norm on light soil, 2,157 m3

potentially accumulated surface runoff yield exceeds 2,000 m3

attributed with 100 availability points (Table 4 and 5).

soils (3,720 m3

The determination of drought risk classes of agricultural land suitable for irrigation is the sum of the attributed availability points of each individual water resource suitable for irrigation of agricultural land (Table 6). Water resources (large water reservoirs, surface watercourses, groundwater and surface runoff yield) are spatially defined and interrelated (Figures 2 - 6). The analysis was conducted with raster layers whose spatial resolution was 100×100 m (1 ha) for the entire study area.

Drought risk assessment for agricultural land suitable for irrigation is divided into 6 classes (Table 6). Class 1 is attributed with zero points and indicates areas with potential absence of available water resources for irrigation and is defined as an area with 'distinct drought risk'. Class 6 is attributed with 400 availability points, as all water resources (included in the research) are potentiality available for irrigation and is defined as area with virtually no drought risk if proper measures are undertaken. Intermediate classes between 2 and 5 have one or more restricted water resources and/or one or more of the unlimited water resources suitable for irrigation.

**Availability points classes**

Slovenia

**Area ha %**

http://dx.doi.org/10.5772/53528

213

Geospatial Analysis of Water Resources for Sustainable Agricultural Water Use in Slovenia

Undefined (urban, rocks, water) 60.896,5 3,01

**Table 7.** Areas (%, ha) classes of availability of water resources for irrigation based on figure 7 for total area of

**Figure 7.** Points of potential availability of water resources for irrigation (based on table 3) in Slovenia at 1 ha resolu‐

tion (100×100 m); dry year with five years return period (80-90 % probability of occurrence)

0 0 0,00 1 - 25 54.137,5 2,68 26 - 50 173.185,7 8,57 51 - 99 122.795,3 6,08 100 - 150 1.406.312,6 69,61 151 - 199 34.017,6 1,68 200 - 250 154.698,3 7,66 251 - 299 7.758,8 0,38 300 - 350 6.401,5 0,32 351 - 399 114,3 0,01 400 0 0,00 **Total 2.020.318,1 100,00**


**Table 6.** Determination of risk classes of agricultural land suitable for irrigation in case of drought from the sum of availability points of water resources for irrigation

## **3. Results**

Due to the characteristics of the spatial analysis of the raster layers (raster cells) with the ArcGIS program tool (Spatial Analyst Tools), areas of certain land use classes and total area of agricultural land suitable for irrigation were slightly lower in comparison with the real situation. However, in the results section we primarily operate with shares of areas, describing availability points of water resources and drought risk classes.

#### **3.1. Water resources availability assessment**

Slovenia has unevenly distributed water resources suitable for irrigation as can be seen from the spatial analysis of availability points (Figure 7) in terms of the dry year with five-year return period.

We detected high availability (151-399 points) of water resources for irrigation in river valleys with alluvial soils (rivers Sava, Drava, Mura, Krka and Vipava), where there is, in addition to surface watercourses, also an easily accessible groundwater and in certain areas (river Vipava) large reservoirs (10 % of case study area) (Table 7). In more than 69 % of the case studies water resources for irrigation is rather poorly available (only 100-151 points), which are mostly a combination of groundwater and surface runoff. On more than 17 % of case study areas, available water resources are extremely low (25 - 99 points), with nearly 3 % of area having only low available groundwater (less than 25 points), whose availability for irrigation is in question due to the high costs associated with borehole drilling.


one or more restricted water resources and/or one or more of the unlimited water resources

1 Distinct 0 No available water resources

212 Current Perspectives in Contaminant Hydrology and Water Resources Sustainability

2 Very high 1 - 99 Only water resources with limited availability

3 High 100 - 199 One water resource with unlimited availability and/or more

4 Medium 200 - 299 Two water resources with unlimited availability and/or

5 Low 300 - 399 Three water resources with unlimited availability and/or

6 None 400 All water resources with unlimited availability

**Table 6.** Determination of risk classes of agricultural land suitable for irrigation in case of drought from the sum of

Due to the characteristics of the spatial analysis of the raster layers (raster cells) with the ArcGIS program tool (Spatial Analyst Tools), areas of certain land use classes and total area of agricultural land suitable for irrigation were slightly lower in comparison with the real situation. However, in the results section we primarily operate with shares of areas, describing

Slovenia has unevenly distributed water resources suitable for irrigation as can be seen from the spatial analysis of availability points (Figure 7) in terms of the dry year with five-year return

We detected high availability (151-399 points) of water resources for irrigation in river valleys with alluvial soils (rivers Sava, Drava, Mura, Krka and Vipava), where there is, in addition to surface watercourses, also an easily accessible groundwater and in certain areas (river Vipava) large reservoirs (10 % of case study area) (Table 7). In more than 69 % of the case studies water resources for irrigation is rather poorly available (only 100-151 points), which are mostly a combination of groundwater and surface runoff. On more than 17 % of case study areas, available water resources are extremely low (25 - 99 points), with nearly 3 % of area having only low available groundwater (less than 25 points), whose availability for irrigation is in

with limited availability

more with limited availability

more with limited availability

**Class Sum of points Definition of water resources availability**

suitable for irrigation.

**Number Drought risk**

availability points of water resources for irrigation

**3.1. Water resources availability assessment**

availability points of water resources and drought risk classes.

question due to the high costs associated with borehole drilling.

**3. Results**

period.

**Table 7.** Areas (%, ha) classes of availability of water resources for irrigation based on figure 7 for total area of Slovenia

**Figure 7.** Points of potential availability of water resources for irrigation (based on table 3) in Slovenia at 1 ha resolu‐ tion (100×100 m); dry year with five years return period (80-90 % probability of occurrence)

## **3.2. Drought risk assessment**

The map of potential availability of water resources for irrigation was further adjusted and classified in accordance to the potential drought risk (Table 6), thus creating a map of agricul‐ tural land suitable for irrigation yet exposed to drought risk at the dry year with five year return period (Figure 8).

**4. Conclusions**

over exploitation of water resources.

This chapter presents a novel methodological approach and findings which substantially contribute to the understanding of spatial water resources availability and drought risk assess‐ ment of agricultural land. The methodology is clear, practical and therefore generally applica‐ ble in any region or on a global level. Methodology is open to adding other water resources, not

Geospatial Analysis of Water Resources for Sustainable Agricultural Water Use in Slovenia

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215

When the spatial analysis of available water quantities for irrigation from water resources is prepared for a certain area (region, state, catchment), it is essential to cooperate with all organizations engaged in regulating water management (e.g. environmental agencies, water and geological institutes and responsible governmental bodies). Water quantities available for irrigation from different water resources are usually regulated by state legislation defining minimal water quantities in the surface watercourses or reservoirs to sustain ecological acceptable flows, for the survival of the organisms in the water bodies. Legislation should also include consideration of the share of total water quantity in the water body which can be abstracted for irrigation of agricultural land, and the share of the water quantity in the water body at ecological acceptable flow that is especially reserved for agriculture and can be abstracted for irrigational purposes. Water reservoirs usually have, in addition, operational regulations defining the share of water reserved for agriculture, recreational activities, or for the conservation of wildlife habitats. Legislation and regulation are key factors to preventing

Spatial analysis of potentially needed water quantities for irrigation should be based on land use classes,typesofcropsandcropmanagement.Thisisespeciallyimportantinthecaseofcropswith high water demand. Furthermore, spatial analysis should include physical and hydrological properties of soils in the area. This is important if soils in the area are light, with a high share of sand, high hydraulic conductivity and low available water capacity. Finally, it is crucial to define the irrigation norm (maximum, average and minimum) for all types of soils and crops grown in the area. This kind of analysis has to be done in cooperation with soil hydrologists, plant physiol‐

To define accessibility or abundance of water resources in this study, we choose to use availability points as a number from 0 to 100. Water accessibility points for water reservoirs and watercourses were determined by the extent of agricultural land (%), which may be irrigated with the water assigned for agricultural use from both sources (0 to 100 points). Water accessibility classes for groundwater were determined on the basis of the hydrogeological map and average cost for borehole drilling, and put into three classes: hard (25 points), medium (50 points) and easy (100 points), defining the availability of groundwater. The determination of abundance points was based on the maximum irrigation norm (drip irrigation) for one hectare of permanent crops (orchards) on light soils and its corresponding optimal reservoir volume for irrigation. If in irrigation area was enough of water for irrigation of orchard on light soils with drip irrigation and maximum irrigation norm, it was given 100 availability points (Table 4). Each subsequent class was determined by 25 availability points less, as it does not facilitate sufficient quantities of surface runoff water for irrigation of all groups of agricultural plants.

ogists, agro-meteorologists and specialist technicians in irrigation systems.

presented here (e.g. waste water), in to the water resources availability assessment.

We conducted a spatial analysis of agricultural land suitable for irrigation in the case study area todefinetheavailabilityofwaterresourcesforirrigation,andtodefinepotentialareasofdrought risk. We identified areas of agricultural land at none, low, medium, high, very high and distinct drought risk. Analysis of the potential drought risks of agricultural land suitable for irrigation showed that more than 34 % (75,868 ha) of the case study agricultural land suitable for irrigation islocatedinareasofveryhighdroughtrisk(1-99points).Nearly50%ofagriculturalland(109,231 ha) is located in areas of high drought risk (100-199 points) and almost 15 % (33,010 ha) in areas of mediumdroughtrisk(200-299).Lowdroughtrisk(300-399)ispresentinonly0.2%ofagricultur‐ al land (442 ha) and is therefore negligible at the macro scale. Based on this analysis we argue that areas of medium and low drought risk should not suffer from water scarcity or drought causing damageincropsproductionandlimitingcropyield,ifappropriateinfrastructureandsystemsfor watertransportandirrigationareinstalled,maintainedandusedintheseareas.Researchanalysis did not detect any areas of agricultural land use suitable for irrigation at either absolute extremi‐ ty of drought risk (0 points and 400 points).

**Figure 8.** Agricultural land potentially suitable for irrigation and exposed to drought risk at dry year with five year return period in Slovenia at 1 ha resolution (100×100 m) (based on table 4)

## **4. Conclusions**

**3.2. Drought risk assessment**

214 Current Perspectives in Contaminant Hydrology and Water Resources Sustainability

return period (Figure 8).

ty of drought risk (0 points and 400 points).

The map of potential availability of water resources for irrigation was further adjusted and classified in accordance to the potential drought risk (Table 6), thus creating a map of agricul‐ tural land suitable for irrigation yet exposed to drought risk at the dry year with five year

We conducted a spatial analysis of agricultural land suitable for irrigation in the case study area todefinetheavailabilityofwaterresourcesforirrigation,andtodefinepotentialareasofdrought risk. We identified areas of agricultural land at none, low, medium, high, very high and distinct drought risk. Analysis of the potential drought risks of agricultural land suitable for irrigation showed that more than 34 % (75,868 ha) of the case study agricultural land suitable for irrigation islocatedinareasofveryhighdroughtrisk(1-99points).Nearly50%ofagriculturalland(109,231 ha) is located in areas of high drought risk (100-199 points) and almost 15 % (33,010 ha) in areas of mediumdroughtrisk(200-299).Lowdroughtrisk(300-399)ispresentinonly0.2%ofagricultur‐ al land (442 ha) and is therefore negligible at the macro scale. Based on this analysis we argue that areas of medium and low drought risk should not suffer from water scarcity or drought causing damageincropsproductionandlimitingcropyield,ifappropriateinfrastructureandsystemsfor watertransportandirrigationareinstalled,maintainedandusedintheseareas.Researchanalysis did not detect any areas of agricultural land use suitable for irrigation at either absolute extremi‐

**Figure 8.** Agricultural land potentially suitable for irrigation and exposed to drought risk at dry year with five year

return period in Slovenia at 1 ha resolution (100×100 m) (based on table 4)

This chapter presents a novel methodological approach and findings which substantially contribute to the understanding of spatial water resources availability and drought risk assess‐ ment of agricultural land. The methodology is clear, practical and therefore generally applica‐ ble in any region or on a global level. Methodology is open to adding other water resources, not presented here (e.g. waste water), in to the water resources availability assessment.

When the spatial analysis of available water quantities for irrigation from water resources is prepared for a certain area (region, state, catchment), it is essential to cooperate with all organizations engaged in regulating water management (e.g. environmental agencies, water and geological institutes and responsible governmental bodies). Water quantities available for irrigation from different water resources are usually regulated by state legislation defining minimal water quantities in the surface watercourses or reservoirs to sustain ecological acceptable flows, for the survival of the organisms in the water bodies. Legislation should also include consideration of the share of total water quantity in the water body which can be abstracted for irrigation of agricultural land, and the share of the water quantity in the water body at ecological acceptable flow that is especially reserved for agriculture and can be abstracted for irrigational purposes. Water reservoirs usually have, in addition, operational regulations defining the share of water reserved for agriculture, recreational activities, or for the conservation of wildlife habitats. Legislation and regulation are key factors to preventing over exploitation of water resources.

Spatial analysis of potentially needed water quantities for irrigation should be based on land use classes,typesofcropsandcropmanagement.Thisisespeciallyimportantinthecaseofcropswith high water demand. Furthermore, spatial analysis should include physical and hydrological properties of soils in the area. This is important if soils in the area are light, with a high share of sand, high hydraulic conductivity and low available water capacity. Finally, it is crucial to define the irrigation norm (maximum, average and minimum) for all types of soils and crops grown in the area. This kind of analysis has to be done in cooperation with soil hydrologists, plant physiol‐ ogists, agro-meteorologists and specialist technicians in irrigation systems.

To define accessibility or abundance of water resources in this study, we choose to use availability points as a number from 0 to 100. Water accessibility points for water reservoirs and watercourses were determined by the extent of agricultural land (%), which may be irrigated with the water assigned for agricultural use from both sources (0 to 100 points). Water accessibility classes for groundwater were determined on the basis of the hydrogeological map and average cost for borehole drilling, and put into three classes: hard (25 points), medium (50 points) and easy (100 points), defining the availability of groundwater. The determination of abundance points was based on the maximum irrigation norm (drip irrigation) for one hectare of permanent crops (orchards) on light soils and its corresponding optimal reservoir volume for irrigation. If in irrigation area was enough of water for irrigation of orchard on light soils with drip irrigation and maximum irrigation norm, it was given 100 availability points (Table 4). Each subsequent class was determined by 25 availability points less, as it does not facilitate sufficient quantities of surface runoff water for irrigation of all groups of agricultural plants.

Drought risk classes have to be developed in a careful manner with a clear distinction between classes. A maximum of six classes is recommended, to maintain comprehensibility and transparency for the reader. Aggregation of classes is useful, but must include sufficient information for the reader to understand the data. The scale needs to have extreme classes which represent areas without potentially available water resources for irrigation and areas with all potential water resources fully available.

[2] Turral H, Svendsen M, Faures JM. Investing in irrigation: Reviewing the past and

Geospatial Analysis of Water Resources for Sustainable Agricultural Water Use in Slovenia

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[6] Wisser D, Frolking S, Douglas EM, Fekete BM, Schumann AH, Vorosmarty CJ. The significance of local water resources captured in small reservoirs for crop production

[7] Matičič B, Kravanja N, Jug M, Lobnik F, Prus T, Rupreht J, Šporar M, Vrščaj B, Kočar I, Knapič M, Hočevar A, Kajfež Bogataj L, Avbelj L, Feguš M, Jarc A, Vrevc S, Bitenc D, Četina A, Pajnar N, Vadnal K, Mikluš I, Snučič F, Pavlovčič M, Tajnšek T, Osvald J, Štampar F, Korošec Koruza Z, Čop J, Vončina S, Vuga I, Ozbič. F, Pišot M, Jereb V, Komel L, Skalin B, Udrih R, Škafar L, Maruša T, Mesarec S, Kovačič I, Pirc V, Juvan S, Burja D, Pintar M, Anzeljc D. Nacionalni program namakanja Republike Slovenije - National Irrigation Programme of the Republic of Slovenia. Ljubljana: University of Ljubljana - Biotechnical Faculty, Ministry for Agriculture, Forestry and Food; 1994.

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looking to the future. Agricultural Water Management 2010;97(4) 551-560.

ments in Europe. Journal of Hydrology 2009;373(3-4) 527-544.

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(accessed 1 December 2010).

across-europe (accessed 1 October 2011).

Practical applications of the geospatial analysis of water resources for sustainable agricultural water use are numerous. The results are important for identifying areas on regional and global level which are best suited for irrigation development in terms of water resources availability. Results are important as they help areas suffering from periodic droughts to draw govern‐ mental attention. This is important as these areas require financial investment in irrigation equipment and irrigation technologies. It helps small growers in remote hilly or karst areas to identify reliable water resources. The results define areas suitable for building small water reservoirs for accumulated surface runoff water, which can help small farm businesses with vegetable or fruit production to be water independent in the drought periods. This is especially important for the population and agriculture businesses in dry, temperate and continental climates with high seasonal differences in precipitation and evapotranspiration.

## **Acknowledgements**

Financial support for this study was provided by the Ministry of Agriculture and the Envi‐ ronment of the Republic of Slovenia and Slovenian Research Agency as part of Targeted Research Program - The competitiveness of Slovenia 2006 - 2013 in 2010. Research project number: V4-1066.

## **Author details**

Matjaž Glavan, Rozalija Cvejić, Matjaž Tratnik and Marina Pintar

University of Ljubljana, Biotechnical Faculty, Agronomy Department, Chair for Agrome‐ teorology, Agricultural Land Management, Economics and Rural Development, Ljubljana, Slovenia

## **References**

[1] Muralidharan D, Knapp KC. Spatial dynamics of water management in irrigated ag‐ riculture. Water Resources Research 2009;45 1-13.

[2] Turral H, Svendsen M, Faures JM. Investing in irrigation: Reviewing the past and looking to the future. Agricultural Water Management 2010;97(4) 551-560.

Drought risk classes have to be developed in a careful manner with a clear distinction between classes. A maximum of six classes is recommended, to maintain comprehensibility and transparency for the reader. Aggregation of classes is useful, but must include sufficient information for the reader to understand the data. The scale needs to have extreme classes which represent areas without potentially available water resources for irrigation and areas

Practical applications of the geospatial analysis of water resources for sustainable agricultural water use are numerous. The results are important for identifying areas on regional and global level which are best suited for irrigation development in terms of water resources availability. Results are important as they help areas suffering from periodic droughts to draw govern‐ mental attention. This is important as these areas require financial investment in irrigation equipment and irrigation technologies. It helps small growers in remote hilly or karst areas to identify reliable water resources. The results define areas suitable for building small water reservoirs for accumulated surface runoff water, which can help small farm businesses with vegetable or fruit production to be water independent in the drought periods. This is especially important for the population and agriculture businesses in dry, temperate and continental

Financial support for this study was provided by the Ministry of Agriculture and the Envi‐ ronment of the Republic of Slovenia and Slovenian Research Agency as part of Targeted Research Program - The competitiveness of Slovenia 2006 - 2013 in 2010. Research project

University of Ljubljana, Biotechnical Faculty, Agronomy Department, Chair for Agrome‐ teorology, Agricultural Land Management, Economics and Rural Development, Ljubljana,

[1] Muralidharan D, Knapp KC. Spatial dynamics of water management in irrigated ag‐

climates with high seasonal differences in precipitation and evapotranspiration.

Matjaž Glavan, Rozalija Cvejić, Matjaž Tratnik and Marina Pintar

riculture. Water Resources Research 2009;45 1-13.

with all potential water resources fully available.

216 Current Perspectives in Contaminant Hydrology and Water Resources Sustainability

**Acknowledgements**

number: V4-1066.

**Author details**

Slovenia

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218 Current Perspectives in Contaminant Hydrology and Water Resources Sustainability


**Chapter 9**

**Changing Hydrology of the Himalayan Watershed**

The Himalayan region is a source of ten major river systems that together provide irrigation, power and drinking water for 1.3 billion people i.e. over 20% of the world's population. The supply and quality of water in this region is under extreme threat, both from the effects of human activity and from natural processes and variation [1]. Population growth is already putting massive pressure on regional water resources, affecting water resource in terms of demand, water-use patterns and management practices. The change in hydrological cycle may affect river flows, agriculture, forests, biodiversity and health besides creating water related hazards [2]. The need for suitable strategies for climate resilient development has policy and governance implications [3]. Adaptation to climate change is the area that should be strength‐ ened through policy advocacy supported by evidence through rigorous research and verified

Re-assessment of true catchments yields under existing and future scenarios of landuse and climate changes is very essential to devise watershed management strategies which can minimize adverse impacts both in terms of quantity and quality. Since trends are still unclear, the extent to which changes can be attributed to variable environmental changes is difficult to determine. It has become imperative to assess ongoing hydrological changes and changes that might occur in future to devise appropriate adaptation measures to foster resilience to future

In the present study, SWAT model developed by United States Department of Agriculture (USDA) [4] has been used to evaluate surface runoff generation, soil erosion and quantify the water balance of a Himalayan watershed in the Northern Pakistan. The response of watershed yield to historical landuse evolution and under variable landuse and climate change scenarios has been studied in order to mitigate the negative impacts of these changes and promote

> © 2013 Ashraf; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

© 2013 Ashraf; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

distribution, and reproduction in any medium, provided the original work is properly cited.

Additional information is available at the end of the chapter

climate change, thereby enhancing water security.

Arshad Ashraf

**1. Introduction**

information.

http://dx.doi.org/10.5772/54492
