People in the unirrigated upland areas suffer if irrigated production depresses crop prices. In urban areas, water control permits the expansion of settlement and economic activity. Scattered remnants of natural forest are replaced over time by exotic species in structure-determined patterns of open space, for example yards, parks and streets. The extent of replacement depends on the strength of rural migration, thus partly on the effect of water redistribution on irrigated and upland agricultural opportunities and on relative food prices. Over time, population densities climb and holding sizes fall in irrigated areas.
People form high-rise homestead forests and shift towards horticultural production.
Tree lines along bunds and paths break and decline. The forest becomes a pattern of household groves. The original riparian forest is replaced by a forest patterned by households and villages, with weak fringes or clumps of residual trees at the margins of cultivation. The upland forest has become a pattern of scattered remnants and planted groves distributed by household or village. The configurations of policies specific to this system are generally contained within national strategies for agricultural and water resource development and for strengthened systems of specialized administration in agricultural areas and around hydroelectric facilities.