Study area
The study was conducted in micro watershed development projects of Sabarkantha and Aravalli districts of Gujarat, India as shown in Fig 1. Latitudinal and longitudinal extent of the basin are between 23.5138°N and 72.7361°E. respectively. The maximum temperature of the study area ranges between 40°C to 42°C and minimum temperature ranges between 9°C to 11°C and the mean relative humidity was approximately 49.6 percent. The average rainfall of study area was 731 mm. This region is an extension of the Aravalli Hills, with a mix of dry deciduous, Procopius and thorny scrub arid forest. The major land use/land cover scenario of the study area include cultivated land, shrub land, forest land, grass land and water bodies. Cultivated land is situated on the steep and undulating slope and mostly, there are conservation measures implemented in different schemes. Sand, loamy and medium black are the three main types of soil found in almost entire districts.
Study method
A set of indicator questions for questionnaire survey, was developed to collect the ground-level agricultural and socio-economic data to evaluate the effects of watershed project implementation. Revised Universal Soil Loss Equation (RUSLE) carried out the soil erosion estimation and change in groundwater was estimated by well inventory and water table fluctuation method. All evaluated indicator values were used to develop the watershed performance benchmarking index (WPBI) for ranking and indexing watershed projects implemented in the study area through the concept of AHP.
Methodology
There were around 180 watershed projects implemented in these districts under IWDP, DPAP and IWMP. Amongst them, 19 watershed projects were selected for study by random sampling covering all three schemes. The hydrological, agricultural, social and economic parameters were considered to evaluate watershed projects in the study area. The parameters before and after watershed implementation were calculated to observe the changes after implementation. In this study, the selected indicators for these parameters have been denoted as per following: (i) Reduction in soil erosion-RSE, (ii) Increase in groundwater table-IGWT, (iii) Change in crop productivity-CCP, (iv) Change in cropping intensity-CCI, (v) Increase in livestock-ILS, (vi) Increase in employment-IEM, (vii) Increase in saving and expenditure capacity-IEX, (viii) Reduction in migration-RMI, (ix) Increase in income-IIN and (x) Benefit-cost ratio-BCR.
The measurement and calculation of the reduction in soil erosion were carried out through the Revised Universal Soil Loss Equation (RUSLE). The measurement and calculation of the increase in groundwater table were carried out by the water table fluctuation method through the well inventory. The agricultural and socio-economic indicators were calculated by the questionnaire survey, joint field visits of the watershed area and beneficiaries and focused group discussions with village communities. The initial data related to the study area’s physical environment and the socio-economic condition is collected from the watershed from July 2000 to June 2018 from the project implementing agency and DRDA, Sabarkantha. Data related to the climatic conditions like rainfall, temperature, humidity, etc. total area, population, soil data and status of the local community were collected from the respective government departments and various agencies.
The analytic hierarchy process (AHP) is a method for organizing and analyzing complex decisions using mathematics and psychology. It was developed by
(Saaty, 1987) and has been refined ever since. AHP tool was used to obtain different criteria weights for each indicator and watershed performance benchmarking index (WPBI) was then calculated based on the criteria weights. The equation developed for WPBI was then validated by statistical analysis and regression to check the significance of the regression model. Finally, the WPBI was calculated based on regression coefficients. Based on the values obtained for each indicator and WPBI, the watershed projects were compared and identified the issues and challenges in implementing watershed projects. The resources of Government Engineering Colleges of Modasa and Godhra affiliated with Gujarat Technological University, Ahmedabad, Gujarat have been utilized for some practical and procedural activities during the study during the years 2015 to 2022.