However, this is still an important source of irrigation in the uplands of Balochistan. In a karez, lined mother wells are dug in the foothills at certain distances apart to intercept the water table high up in an alluvial fan, then water is led to the valley floor under gravity. These mother wells are connected underground through tunnels. A series of mother wells take water to cultivable lands. Sometimes, a karez may take perennial water flow as far as 40km.
Water is rotated from distributor to distributor and within sections of a distributor.
In recent developments, concrete versions of flow dividers can be seen. Sailaba Farming Sailaba indicates moisture conservation through flooding fields during the rainy season. Sailaba farming is extensive in most parts of Balochistan, Pakistan, particularly in the highlands. During the rainy season, flood water is harvested in catchments for crop production. This technology is extremely important in the kind of region where aridity prevails and mountain terrain accelerates water runoff.