SENSITIVITY ANALYSIS - Department of Agriculture and ...

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UKDM ENVIRONMENTAL MANAGEMENT FRAMEWORK Table 5: Sensitivity Ratings assigned to Category: Terrain & Geotechnical Conditions Category Sensitivity Criteria Attributes Rating TERRAIN & GEOTECHNICAL CONDITIONS Development Potential Zones DPZ 1: River channels and dams DPZ 2: Wetlands and floodplains DPZ 3: Very steep slopes; >18 o DPZ 4: Low gradient slopes with clay-rich soils DPZ 5: Low gradient slopes with duplex soils DPZ 6: Medium gradient, rocky slopes DPZ 7: Medium to high dune topography with poorly drained interdune depressions DPZ 8: Low dunes with less interdune wetlands DPZ 9: Low gradient slopes and shallow soils on bedrock DPZ 10: Deep sandy soils and low gradients VH VH VH VH M M M L L L Figure 12: Terrain & Geotechnical Sensitivity Map Draft Desired State Report (May 2013) Page 35
UKDM ENVIRONMENTAL MANAGEMENT FRAMEWORK 3.1.4 Geohydrology Most of the municipal area falls within two hydrogeological regions defined on the basis of lithology and climatology, namely: • Northern Coastal Plain Hydrogeological Region - This region lies east of the Lebombo mountains and comprises the Cretaceous Zululand Group rocks overlain by Pliocene, Pleistocene and Holocene dune deposits. The development potential is low to medium. The associated aquifers are vulnerable to pollution. Depending on the level of dependence of the rural settlements the risk can be between low and medium. However, nothing is known about the sources of pollution and these needs to be determined. • Southern Lebombo Hydrogeological Region - With five irrigation boards in this region it is reasonable to assume that groundwater is used for irrigation purposes. However, this assumption needs to be tested and if found to be correct the level of groundwater use must be determined. No protection actions can be defined unless the level of use and potential threats to groundwater has been determined. Most of the rural settlements are largely or wholly dependent on groundwater for their domestic supplies and thus represent a large component of the domestic water use sphere. However, very little, or no data are available on, a) their dependence on groundwater, b) their vulnerability to droughts, and c) the volumes being abstracted, all of which is needed to define the level of the impact on the groundwater resources of the underlying areas. No proactive action can be taken in terms of mitigating either vulnerability or augmentation of the supply where there are shortages. With the shortage of information on these hydrogeological regions, it is not possible to provide conclusive comments on their sensitivity on a more refined scale. Nonetheless, a coarse sensitivity map was prepared based on the sensitivity rating tabulated below. Table 6: Sensitivity Ratings assigned to Category: Geohydrology Category Sensitivity Criteria Attributes Rating GEOHYDROLOGY Vulnerable Groundwater Zones Northern Zululand Coastal Plain Hydrological Region Southern Lebombo Hydrological Region VH M Draft Desired State Report (May 2013) Page 36
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