Investigation of Fresh Water Harvesting from Playa's Wetlands

Playas are low-lands which is considered to be the locations of accumulation of superficial and ground waters from higher elevations and these waters have different types of salts and various salinity level. Therefore, because of lack of rainfall and fresh-water both for human and animal useage or even for plants, it is needed to apply proper methods to harvest fresh water from these saline-waters to develop agricultural and animal husbandry industry in this areas. Therefore, the research will try to investigate fresh water harvesting from playa’s saline waters with the aid of saloar enegy and without implementation of import and complicated technology. The method is called Evaporating Water Harvesting (EWH). In this method, to install plastic covers on playa’s wetlands, productive fresh water obtained by condensation of evaporated water from soil surface (disturbed and undisturbed suface) was measured. Factors such as soil genesis, soil’s salts, water table, rate of saolar radiations and atmosphere temperature changes, had influence on the rate and term of water harvesting. The result showed that Daily average of gathered water from 1m2 soil surface in disturbed statement was 0.3 liter. The Minimum and maximum rates were 0.1 and 0.35 liter in May and July, respectively and Daily average of gathered water from 1m2 soil surface in undisturbed statement was 0.03 liter. The Minimum and maximum rates were 0.0 and 0.05 liter in May and July respectively. Then SPSS 11 software for being any relationship between sites’s water harvesting and environmental factors (such as water table, temperature, relative humidity, sun shine hours) was used. Results showed that the mean correlation of 99 percent had been between rate of sites’s water harvesting and temperature and water table factors and 95 percent to sun shine hours. At last, water table map was drawn. This method has some advantages such as producing fresh waters in playas, simplicity and being conomical and so on (see result section), and some disadvantages including limitation by using plastic covers, calcic and gypsic horizons in soil, not being usable in higher water tables (>3m).