Abstract

Surface water is an important resource that can create tensions between different countries sharing the same water sources to know that the agriculture is considered as the last sector that exploits less water compared to the industry which uses very large water quantities. The future strategies of agricultural development in the most of these countries depend on the ability to maintain, improve and expand irrigated agriculture. In this light, this chapter is written in the way to show some steps of the evaluation of surface water for irrigation purpose. The results obtained from this research make it possible to evaluate the suitability of surface water for irrigation and to draw useful recommendations for dam managers and farmers.

Keywords: surface water, hydro chemical analysis, irrigation purpose, water quality index

### 1. Introduction

Surface water is an essential natural resource that plays a vital role in human life and has an important role in drinking, irrigation and economic sectors. According to FAO statistics, 20% of the land is irrigated but produces 40% of the crops [1]. Irrigation is an effective way to improve productivity significantly. However, there are environmental risks associated with irrigation, especially water stagnation and increased salinity. Agricultural irrigation is a factor of increase and diversification of crops. This is why its development must be encouraged in the world through agricultural, international, national and community policies [2]. For this reason, that successive governments have so far sought to harden the right to water while protecting the interests of irrigators. This strategy, if explained by the social contract that binds the state to farmers, is nonetheless debatable [3]. The priority is no longer today to increase yields among the highest in the world, but to ensure the continuity of drinking water supply services, the preservation of aquatic ecosystems and sufficient water levels to respond industrial needs. The salinity of water has increased in many watersheds around the world and the use of non-traditional resources, bet on the use of available resources, increases efficiency, waste reduction and water maintenance quality establishing surveillance networks, developing and setting standards, and enacting the necessary laws to protect them from

pollution [4, 29]. The importance of developing a comprehensive strategy for water demand management appears to be a consequence of the exacerbation of the problem of scarcity of water resources due to drought, which has become more frequent with a longer duration [5]. Therefore, the main goal of this chapter is to evaluate suitability of surface water for irrigation purpose by appropriate parameters and indices in Koudiate Medouar dam in northeast of Algeria.

About 48.72% of the population of Batna Wilaya, or 682,000 inhabitants, drink water from this dam that supplies the cities of Batna, Tazoult, Timgad, Ain Touta, Barika, Arris and Ouled Reach in the Wilaya of Khenchela. The climate of the study area is semi-arid, characterized by high temperatures and low rainfall. The average annual rainfall is about 370 mm, while the annual average temperature is

Suitability and Assessment of Surface Water for Irrigation Purpose

DOI: http://dx.doi.org/10.5772/intechopen.86651

Surface water samples collected from the dam basin during a year from February 2017 to January 2018. During water sampling, all samples were filtered on-site by 0.45-μm filter. The water samples were stored in 500-ml high-density polyethylene bottles (HDPE) for laboratory analyses. All water samples were kept at 4°C until they were analyzed with using standard methods APHA [7]. Measurements of pH and electrical conductance (EC) were carried out in field with the use of a portable multi-parameter analyzer Hem [8]. Major cations and anions including calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), sulfate (SO4), bicarbonate (HCO3), chloride (Cl) and nitrate (NO3) were measured in laboratory. Total hardness (TH) and Ca were volumetrically analyzed using standard EDTA. Mg was calculated by taking the difference between TH and Ca. A flame photometer was used to estimate Na and K. HCO3 and Cl were analyzed by titration with standard HCl and AgNO3, respectively. SO4 was determined using a turbidimetric procedure. NO3 was analyzed using the colorimetric method. The reliability of the data set generated was verified through electrical neutrality by the following equation:

Error of ion balance <sup>¼</sup> <sup>∑</sup>Cations � <sup>∑</sup>Anions

The analytical data were considered doubtful beyond an error of �5% [9].

The statistical summary of the data used in this study is represented in Table 1. The results show that pH values varied from 7.4 to 7.8 with a mean of 7.5, indicating that the water is consider as a slightly alkaline water [10]. Electrical conductivity values express the amount of dissolved solids in the water sample. Water samples has EC values that ranged from 1040 to 1800 μS/cm with an average of 1349 μS/cm. EC of the surface water samples was above the fixed value of 1000 μS/cm by WHO [11]. The average values of Ca, Mg, Na and K are 94.04, 42.72, 93.92 and 1.01 mg/L, respectively. The order abundance of the major cations as follows Ca > Na > Mg > K, where the calcium and sodium are the dominate cations in surface water. The calcium values are generally upper than the limits set in WHO guides [11]. The high concentrations of Ca and Na are explained by the ion exchange process between sodium and calcium elements which leads to the precipitation of CaCO3 in the soil profile. The order abundance of the major anion from the highest to the lowest is HCO3 > Cl > SO4 > NO3, indicating that bicarbonate and chloride are the dominants anions in the surface water. The concentration of HCO3 is varied from 134.2 to

∑Cations þ ∑Anions

� 100 (1)

around 15°C [6].

3. Methodology

3.1 Water sampling and analysis

4. Results and discussion

4.1 Descriptive statistics

5
