Zambia has a large number of protected areas. Here we use WaterWorld 2.87 to compare scenarios of:
(a) intensive agricultural development outside these PAs at 10 trimes the current rate with the PA left intact to provide hydrological ES
(b) intensive agricultural development inside and outside of these PAs
(c) eco-efficient agricultural development outside PAs including the use of buffer strips, low input techniques and terracing of steep slopes
Baseline hydrology
The baseline hydrology for western Zambia shows a strong north-south gradient in water balance reflecting the distribution of wind-driven rainfall and actual evapotranspiration coupled with inputs from fog.
Land use scenarios
In the intensive outside of PAs scenario (a) we apply the following rules:
...and see land use change throughout the unprotected areas of the region and this leads to increases in water balance for some regions and decreases for others according to the balance between change in actual evapotranspiration (decreases because of lower tree cover) and change in fog interception (also decreases in foggy areas because of lower tree cover), leading to decreases in runoff (though these are small in percentage terms) and an increase in the seasonality of the remaining runoff. Significant increases in the human footprint on water quality also occur even in percentage terms at the sites of the new agricultural land and downstream.
In the intensive outside and inside of PAs scenario (b) we apply the following rules:
...and see land use change throughout the north of the country. This leads to greater decreases in runoff though these are again small in percentage terms. This leads to much greater human impact of water quality locally but the effect downstream does not change significantly.
The eco-efficient agricultural development outside PAs is a combined scenario including land use change as per scenario (a) but also the use of buffer strips, low input techniques and terracing of steep slopes. The scenario is complex as:
...and the implications are a change in the distribution of croplands, forests, protected areas, cropland intensity and slope gradient. These conservation focused changes lead to increases in water balance in some areas and decreases in others relative to the baseline, resulting in an overall increases in runoff in some areas and decreases in others. Impacts on water quality are significant in the agricultural areas but, because of the low input regimes and the user of riparian buffer strips of these areas, do not propagate far downstream. In some areas water quality improves compared to the baseline as existing agriculture comes under better management.