**2. Climate and its variability at Mid hill Hawalbagh, Almora**

The climate variability observed based on past years data of rainfall and temperature is summarized in next section. The rainfall variation showed that out of 55 years, the 24 years rainfall was below the normal rainfall. The annual rainfall showed decreasing trend and the rainy days with 50, 75 and 100 mm of rainfall are found increasing. Whereas, 25 mm rainfall rainy days are decreasing.

#### **2.1 Rainfall characteristics**

The precipitation is the primary input in the hydrological cycle and dominantly influences the complex hydrological phenomena. Precipitation is the main source of fresh water. Precipitation is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation include drizzle, rain, sleet, snow, graupel and hail. Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as sleet, snow, and hail. The rainfall information is needed for management of natural resources and crop planning. Rainfall amount, intensity and its distribution are prime factors affecting plant growth, soil erosion and flood problems. This is more pertinent to state like Uttarakhand hills, which has only 10% area under irrigation. The distribution of rainfall in hills is very important because it not only influences hills but also downstream locations in plains. The excess rainfall may aggravate erosion in hills and floods in low-lying areas while deficit may cause drought and reduced river flow. Knowledge of rainfall pattern in a given geographical location enables the development of suitable strategies for agricultural planning and implementation.

#### *2.1.1 Annual rainfall*

Annual rainfall (1964–2018) data recorded at Agro-Metrological Observatory, Hawalbagh (Almora), showed variation from 650.8 mm in 1974 being lowest to 1496.0 mm in 1971 being highest with a mean of 994.8 mm. The standard deviation (SD) and coefficient of variation (CV) of annual rainfall were 208.7 mm and 21.0 per cent, respectively. It was observed that rainfall in 24, out of 47 years was higher than the mean. The annual average rainy days were 67 with SD 10.5 and CV 15.6 percent. The maximum number of rainy days (90) was recorded in the year 1977 with rainfall (1088 mm) and minimum (49) with rainfall (852.1 mm) in 1964. The highest annual rainfall (1496.0 mm) was recorded during 1971 in 85 days, while

*Climatic Variation and Its Impacts on Yield and Water Requirement of Crops in Indian Central… DOI: http://dx.doi.org/10.5772/intechopen.94076*

highest rainy days (90) received 1088 mm rainfall in 1977, respectively. Annual rainfall showed decreasing trend over the years.

## *2.1.2 Monthly rainfall*

villages need to be considered while implementing various methods of forestry. Various agroforestry practices can be used based on climate of the place and utility,

(2014), will give a major boost to the agroforestry [20]. In 1981, our country's population was 236.7 million, which increased to 1.21 billion in 2011. However, there has been no increase in the country's geographical area. If population growth continues at this pace, by 2020 the population of our country will be more than 1.30 billion. Thus, the effects of increasing population and urbanization have impact on loss of forests, increased soil erosion and atmospheric pollution. Therefore, at present the agro-forestry tree planted portion will not only prevent soil erosion but also increase its productive power and will help to maintain environmental balance. Planting trees with crops will increase the returns from per unit land [19].

**2. Climate and its variability at Mid hill Hawalbagh, Almora**

found increasing. Whereas, 25 mm rainfall rainy days are decreasing.

The climate variability observed based on past years data of rainfall and temperature is summarized in next section. The rainfall variation showed that out of 55 years, the 24 years rainfall was below the normal rainfall. The annual rainfall showed decreasing trend and the rainy days with 50, 75 and 100 mm of rainfall are

The precipitation is the primary input in the hydrological cycle and dominantly influences the complex hydrological phenomena. Precipitation is the main source of fresh water. Precipitation is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation include drizzle, rain, sleet, snow, graupel and hail. Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as sleet, snow, and hail. The rainfall information is needed for management of natural resources and crop planning. Rainfall amount, intensity and its distribution are prime factors affecting plant growth, soil erosion and flood problems. This is more pertinent to state like Uttarakhand hills, which has only 10% area under irrigation. The distribution of rainfall in hills is very important because it not only influences hills but also downstream locations in plains. The excess rainfall may aggravate erosion in hills and floods in low-lying areas while deficit may cause drought and reduced river flow. Knowledge of rainfall pattern in a given geographical location enables the development of suitable strategies for agri-

Annual rainfall (1964–2018) data recorded at Agro-Metrological Observatory, Hawalbagh (Almora), showed variation from 650.8 mm in 1974 being lowest to 1496.0 mm in 1971 being highest with a mean of 994.8 mm. The standard deviation (SD) and coefficient of variation (CV) of annual rainfall were 208.7 mm and 21.0 per cent, respectively. It was observed that rainfall in 24, out of 47 years was higher than the mean. The annual average rainy days were 67 with SD 10.5 and CV 15.6 percent. The maximum number of rainy days (90) was recorded in the year 1977 with rainfall (1088 mm) and minimum (49) with rainfall (852.1 mm) in 1964. The highest annual rainfall (1496.0 mm) was recorded during 1971 in 85 days, while

The provision of agro-forestry-based industries in National Agroforestry Policy

benefits and on need basis [7, 9, 19].

*Agrometeorology*

**2.1 Rainfall characteristics**

cultural planning and implementation.

*2.1.1 Annual rainfall*

**12**

The mean monthly rainfall (1964 to 2018) is presented in **Table 1**. It is evident from table that each month received more than 130 mm rainfall during June to September. The highest rainfall (240.2-mm) with highest 14 rainy day was recorded in July followed by August with mean rainfall (210.0 mm) with average 13 rainy days. The monsoon months (June to September) regarded as effective months of rainfall or wettest months of the year. The average rainfall during October, November and December was 22.8, 6.2 and 20.3 mm respectively. The average rainfall during January, February and March months was 39.9, 50.7 and 42.4 mm with rainy days 3.0, 4.0 each for later two months 4.0 respectively. The rainfall of pre monsoon months *i.e.* the April and May was recorded 32.0 mm and 61.7 mm with rainy days 3.0 and 5.0 days respectively (**Table 1**).

#### *2.1.3 Annual and seasonal rainfall and its variability*

The annual rainfall showed decreasing trend (**Figure 1**). It was recorded that mean annual rainfall was 994.8 mm, highest annual rainfall (1496.0 mm) in the year 1971, lowest annual rainfall (650.8 mm) in the year 1974 and highest rainfall in single day (167.0) on 18th September 2010. Whereas, mean annual rainy days (68 days), highest rainy days in year (90 days) in the year 1977, lowest rainy days (49 days) in the year 1964 and 1966. The highest rainfall 72.3% occurred in monsoon season followed by summer (13.6%) winter (11.1%) and least in post monsoon (3%).


#### **Table 1.**

*Mean, monthly rainfall characterization (mm) of month along with rainy days and CV (1964–2018).*

**3. Estimation of crop water requirement in study area**

*DOI: http://dx.doi.org/10.5772/intechopen.94076*

ETo <sup>¼</sup> <sup>0</sup>*:*408Δð Þþ Rn � <sup>G</sup> <sup>γ</sup> <sup>900</sup>

ETo = reference evapotranspiration [mm day�<sup>1</sup>

Rn = net radiation at crop surface [MJ m�<sup>2</sup> day �<sup>1</sup>

T = mean daily air temperature at 2 m height [°C].

es � ea = saturation vapor pressure deficit [kPa].

climate, soil evaporation and crop growth stages [21].

ETc = crop evapotranspiration [mm day�<sup>1</sup>

ETo = reference crop evapotranspiration [mm day�<sup>1</sup>

Kc = crop coefficient [dimensionless].

**3.2 Gross irrigation requirement**

u2 = wind speed at 2 m height [m s�<sup>1</sup>

*γ* = psychrometric constant [kPa °C�<sup>1</sup>

G = soil heat flux density [MJ m�<sup>2</sup> day �<sup>1</sup>

Δ = slope of vapor pressure curve [kPa °C�<sup>1</sup>

Δ þ γð Þ 1 þ 0*:*34u2

].

].

].

].

The crop evapotranspiration, (ETc) is calculated by multiplying the reference crop evapotranspiration, (ETo) by crop coefficient (Kc). Consequently, different crops will have different crop coefficients. Kc value varies with the type of crop,

].

The gross irrigation requirement (GIR) accounts for losses of water included during conveyance and application of irrigation water to the field. The gross irrigation requirement is calculated by the ratio of net irrigation requirement to the

<sup>T</sup>þ<sup>273</sup> u2ð Þ es � ea

].

].

ETc ¼ Kc � ETo (2)

].

(1)

form:

Where,

**3.1 Crop coefficient**

Where,

irrigation efficiency.

**15**

Water requirement of the crops defines the quantity of water needed to meet the water losses through evapotranspiration of a disease-free crop under non restricting soil conditions, including soil, water and fertility and achieving the full potential under a given soil environment in a given time. Water requirement of the main *Kharif* and *Rabi* season crops (*i.e.* Vegetable pea, Barley, Rajma, Tomato, French Bean, Chili, Rice, Wheat, Maize, Soyabean, Okra, Mustard, and Cow pea) were calculated on the basis of Reference crop evapotranspiration (ETo) on the monthly basis by using CROPWAT model based on FAO-Penman-Monteith's semi-empirical equation. The required weather data (min. and max. Temperature, rainfall, sunshine hours, wind speed, etc.) was collected from the automatic weather station. Reference evapotranspiration (ETo) expresses the evaporative index of the atmosphere at a specific location. It is independent of crop type, stage of development and management practices. The reference evapotranspiration had been calculated using this Equation [21] in the following

*Climatic Variation and Its Impacts on Yield and Water Requirement of Crops in Indian Central…*

**Figure 1.** *Mann- Kendall test statistics for annual and rainfall data of different seasons.*
