Investigation of Fresh Water Harvesting from Playa’s Wetlands

Abstract

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