Socio-Economic and Environmental Dynamics Associated with Karez System in Quetta Valley

Abstract

The karez system can be regarded as unique global heritage. This technology was developed many centuries ago in arid and semi-arid regions of Western China, Middle East, North Africa, Iran, Afghanistan and parts of Baluchistan, Pakistan. The System uses underground canal, which has a series of wells for maintenance purposes. Karez is a sustainable and stable irrigation system and the main success factor of the system is that, it taps the water passively and therefore not responsible for groundwater table depletion. However, this has a downside as well and depends on seasonal water flow fluctuations for collecting discharge. There are approximately 1053 functional karezes in the northwest corner of Baluchistan bordering with Afghanistan and Iran having more than 22,000 LPs discharge that is used for irrigating more than 27,000 ha. However, some 270 karezes are not functional and could be restored appropriately. In this study, an attempt has been made to develop detailed inventory of three oldest karezes existing in Quetta valley namely, Zardad, Sanjidi and Chashma Achozai karezes by integrating their historical data, structural properties and physio-chemical parameters water. Furthermore, socio-economic impacts, caused by its mismanagement, non-functionality and lack of water resource are also identified with sustainable water management plan for the revival of these respective karezes also proposed. A concise questionnaire was developed and distributed among local community of command area for inventory, which includes historical data, physical environment, command area, parameters of karezes, agriculture, reasons for getting dry or partial functioning of Karez. In the field work, water sample were collected from each of the three sites of Karezes and tube wells for water quality tests. Soil infiltration test and texture analysis using sieve method of each site were also performed. The losses measured due to seepage in the Chashma Achozai karez and Sanjidi karez from daylight point to command area were found to high i.e. 52 and 66 percent respectively. Physical parameters of collected sample from both tube wells and karezes were tested for pH, electrical conductivity, TDS and turbidity. Average pH of water ranged between 7.2 – 8.4 and turbidity of karez water > 7.2 NTU while that of tube wells was < 3. Other chemical parameters like Ca, Mg, K, Na, HCO3, NO3, SO4, Cl, Alkalinity and Hardness were found to be in normal range and suitable for drinking as well as irrigation purposes. Soil in the command area are Sandy loam, Sand and Sandy clay loam and these are good for agricultural proposes. It is recommended that further actions need to be taken to rehabilitate karezes by managing it properly, provide proper slope to channel, construction of check dams and use of irrigation water applying modern techniques.