Assessing socio-environmental sustainability at the level of irrigation and drainage network

Abstract

Assessing pre- vs. post environmental and social effects of present irrigation projects is vital to provide sustainable socio-environmental roadmaps for the upcoming similar development projects. Such sustainability was assessed for the first time in the present study at a 20- year old irrigation and drainage network (TIDN) area in the north of Iran covering about 70 thousands ha. A 32- year period data on groundwater level and surface- and groundwater quality as well as data on harvested area and crop production was analyzed to evaluate environmental sustainability. Inverse distance weighting (IDW) method was used to prepare the zoning maps and to analyze the descriptive data. Social response to the TIDN was assessed using a cross-sectional survey through completing a questionnaire. The raw data obtained from the questionnaires were analyzed using SPSS software. During the operation of the TIDN, the cropping area increased gradually from about 34,000 ha to about 53,000 ha. In this period, the average yield of early- and late- matured rice (Oryza sativa L.) varieties, predominant crops grown in the area, increased steadily from about 5300 to 6700 kg ha−1. Groundwater table depth declined gradually with an annual reduction of 7.5 cm mainly due to agricultural intensification. Groundwater quality parameters such as electrical conductivity, total dissolved solids, sodium, chloride, bicarbonate and magnesium decreased substantially especially in the semi- deep wells, while nitrate concentration showed a little increase without human effects. The TIDN project improved rural sustainability, hope feeling, security feeling, tourism development, cultural development, trust, social solidarity, social participation and life quality. The results indicate that similar comprehensive analyses can provide an important contribution to assess socio- environmental sustainability in irrigated catchments.