AguaAndes (WaterWorld) was run to better understand the distribution of water and water productivity in Central America with some sample intervention scenarios for improving water productivity and the delivery of ecosystem services downstream.
Baseline water and water productivity
The hydrological baseline analysis was produced at 1km resolution on the basis of MODIS land cover (year 2000) and WorldClim rainfall (1950-2000). The baseline water balance (rainfall+fog minus actual evapotranspiration) produced by WaterWorld indicates all positive water balance but with significant variability across the region. Masked for areas with elevation >=1000m, we see some very wet areas in Guatemala and Costa Rica but much drier mountain regions throughout Honduras, El Salvador and Nicaragua.
Actual evapotranspiration is much higher in aquatic and coastal zones and generally low in the mountains. AET for all croplands is shown here covering 36% of the area and with a mean of 240 mm/yr, for all pastures is shown here with a mean of covering 36% of teh area and with a mean of 310 mm/yr.
Table 1 shows potential evapotranspiration (PET), actual evapotranspiration (AET), vegetation productivity per unit AET (water productivity for all vegetation in the given class) and crop productivity per unit of AET (water productivity for intensive croplands only), all averaged over the tile. Maps of water productivity for irrigated intensive croplands are shown here, for all intensive croplands are shown here and for intensive pastures are shown here.
In addition to the water productivity of water we can examine ecosystem services to downstream users including water quality (dominated by the agricultural and pastoral footprint), gross soil erosion (and also in the watersheds of dams) and sedimentation as well as water stress for agricultural domestic and industrial uses
Eco-efficiency
By implementing eco-efficient agricultural techniques in a scenario that converts 50% of agricultural land at elevations greater than 1000m to a 50% reduction in agricultural inputs (manures, fertilisers, pesticides, herbicides) through more focused and precision application, if we can maintain production then we might reduce significantly the downstream impacts on water quality. If invested in, the scenario would increase eco-efficiency in these areas. The resulting improvements in water quality would be focused on these areas locally and downstream.
Table 1 Water use and water productivity by land cover and crop type for central America