Rainfall surpluses have also resulted in the complete recharge of most water sources (pans, shallow wells, boreholes) and livestock trekking distances to watering points from grazing fields have decreased to historically low levels.
Even though the grass cover is considered to be negligible, in a year with surplus rainfall, the grass can grow explosively and suddenly disappear for several years.
The solubility product is greater in the warm dry season when there is a net upward water flux from the groundwater table to the surface soil, than in the cooler wet season when salts are leached from the surface soil by surplus rainfall.
A water balance model (monthly precipitation minus monthly ET) defines three broad climate zones along the sampling transect: an arid zone with moisture deficit in every month, an intermediate zone with moisture deficit during low-rainfall summer months and moisture surplus during high-rainfall winter months, and a humid zone with moisture surplus during every month.
Where precipitation is in excess of crop requirements; in this case the strategies are to reduce rainfall erosion, to drain surplus run-off and store it for subsequent use.
However, the position of Chogha Golan in a diversified region in terms of deficits or surpluses of rainfall suggests a potential for considerable environmental fluctuations in relation to inter-annual weather variability and climate change.
Risk is highest in areas with extended high annual rainfall, high soil moisture and surplus water.
During the first half of November 2012, extreme rainfall events led to an annual surplus of over a third of normal.
Because of adequate and reliable rainfall, the district can produce a surplus of crops (forestry and horticultural products, pyrethrum, cereals, fruit trees, tea).
The additional rainfall for the year also contributed to a welcomed surplus of feed provided by unusual regrowth by their winter tricale crop.
