LIMPOPO RIVER: Hydrology and geohydrology

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Map of the LIMPOPO River

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HYDROLOGY
The Crocodile (west)/Marico Water Management Area (Marico): 
The Marico and Crocodile Rivers form the headwaters of the Limpopo at their confluence. The flow in the Marico River (MAR  126 million m3/year) is highly variable and intermittent. There are two major storage reservoirs that regulate the flow in the Marico River, namely the Marico Bosveld Dam in the upper catchment and the Molatedi Dam further down-stream. There are several other dams, such as the Klein Maricopoort and Sehujwane Dams, from which water is mainly used for irrigation along the Marico River, particularly downstream of Marico Bosveld Dam. The Ngotwane River (MAR  14 million m3/year) is a tributary of Limpopo River. It flows into Botswana before turning and joining the Limpopo River. (Ref.4)

The surface water runoff is highly variable and the available surface water resource has been fully developed.  (Ref.4)

The Crocodile (west)/Marico Water Management Area (Crocodile):
The natural surface Mean Annual Runoff (MAR) is approximately 646 million m3/annum. (Ref.5)

Streamflow reduction due to invasive alien vegetation has not been considered to have a large impact on water availability in this catchment. More survey work in co-operation with Working for Water would need to be conducted to confirm this assumption.(Ref.5)

The Crocodile River system is regulated by 9 major dams, which are the  Rietvlei, Hartbeespoort and Roodekopjes dams in the Crocodile,  Roodeplaat and Klipvoor dams in the Apies/Pienaars, Olifantsnek, Bospoort, Lindleyspoort and Vaalkop dams in the Elands River area. (Ref.5)

The Limpopo Water Management Area:
The distribution in runoff in the north/northwest area is directly associated to the higher than average rainfall in the mountainous areas of the Waterberg and Soutpansberg ranges. Catchments such as the Mokolo, which have large areas situated in the mountainous ares of the Waterberg therefore have much higher unit runoffs than catchments such as the Sand and Matlabas which are situated in predominantly flat areas of the catchment. The natural runoff from the main tributaries are as follows (Ref.1):
      Tributary   Natural runoff (million m3/annum)        
      Matlabas   49        
      Mokolo   312        
      Lephalala   142        
      Mogalakwena   255        
      Sand River   64        
      Nzhelele   89        
      Nwanedi   25        

The main rivers in the north-east/east are the Luvuvhu, Shingwedzi and Letaba rivers, which all flow in an easterly direction through the Kruger National Park. The Shingwedzi River first flows into the Rio des Elephantes (Olifants River) in Mozambique, which then joins the Limpopo River. The two main tributaries of the Letaba River, the Klein and Groot Letaba, have their confluence on the western boundary of the Kruger National Park, whilst the Letaba River flows into the Olifants River .

The Luvuvhu/Letaba Water Management Area:
The natural runoff from the main tributaries are as follows (Ref.2):
    Tributary   Natural runoff (million m3/annum)          
    Luvuvhu   121          
    Mutale    22          
    Groot Letaba   133          
    Klein Letaba    21          

The Letaba River catchment covers a total area of 13 400kmē and the Shingwedzi River catchment covers a total area of 5 600kmē. The Letaba River catchment is drained by the Groot Letaba River and its major tributaries the Klein Letaba, Middle Letaba, Letsitele and Molototsi rivers. The Shingwedzi River and its major tributaries the Shisha, Mphongolo and Phugwane drain the Shingwedzi River catchment.(Ref.2)

The Olifants Water Management Area:
The available water resource is made up of surface water and groundwater. The mean annual runoff (MAR) for the Olifants Water Management Area is 2042 million m3/a (Ref.3)
    GEOHYDROLOGY                                    
The Crocodile (west)/Marico Water Management Area (Marico): 
Groundwater in Marico  & Upper Ngotwane area is an abundant source of water because of the geology. Groundwater is important at two levels, that is  there are high yielding dolomitic aquifers and local groundwater sources are available for rural water supplies. Overall, the available groundwater resources within the catchment are under-utilised, although this clearly depends both on the groundwater occurrence and the demand. Even weaker groundwater occurrence areas can often provide more than  25 litres per person per day. Groundwater is the main source for rural water supplies. (Ref.4)
The Crocodile (west)/Marico Water Management Area (Crocodile):
Groundwater resources are available throughout the entire catchment, but in varying quantities depending upon the hydrogeological characteristics of the underlying aquifer. Globally it is estimated the overall groundwater recharge to the catchment amounts to some 260 million m3/annum assuming recharge of approximately 2% of the mean annual rainfall of approximately 450mm. Some 125 million m3 of groundwater is used annually, theoretically therefore, up to 135 million m3/annum of annual recharge is still available for exploitation. Away from the urban areas of Johannesburg and Pretoria many parts of the Crocodile West catchment are heavily populated and widespread rural communities are a feature of the area, in particular the districts of Moretele I, Odi I and Odi II north and NW of Pretoria, Bafokeng and Mankwe north of Rustenburg. Groundwater is the main source of water supply to the rural communities except for the Odi I and Moretele I where reticulated supplies are available for the more densely populated southern parts of the districts. There is extensive use of the groundwater resources of the dolomite aquifer NE of Johannesburg, south of Pretoria and NW of Krugersdorp where large abstraction for irrigation, domestic, industrial and municipal supply is practised. (Ref.5)
The Limpopo Water Management Area:
Groundwater is available and widely used throughout the area, but in varying quantities depending upon the hydrogeological characteristics of the underlying aquifer. Much of the Limpopo catchment is populated with widespread rural communities. This is especially the case for the old Lebowa and Venda homeland areas. Groundwater is the main source of water supply to these rural communities although surface water is also used conjunctively where this is available. Groundwater is also used widely for irrigation. The most intensive use of groundwater resources is from the deeply weathered and fractured granite north of Polokwane and in the area around Dendron where large abstractions for irrigation and domestic supply is practiced. Groundwater is used to supply the platinum mines west of Mokopane. (Ref.1)
The Luvuvhu/Letaba Water Management Area:
Groundwater resources are available throughout both the Luvuvhu and Mutale catchments, but in varying quantities depending upon the hydro-geological characteristics of the underlying aquifer. The central parts of the Luvuvhu catchment are heavily populated and widespread rural communities are a feature of the area. Many communities rely on groundwater although conjunctive use schemes (surface and groundwater) are also widespread. (Ref.2)

Groundwater resources are available throughout the Letaba and Shingwedzi catchments, but in varying quantities depending upon the hydrogeological characteristics of the underlying aquifer. Parts of the Letaba catchment are heavily populated and widespread rural communities formally in Venda and Gazankulu are a feature of the area. Many communities rely on groundwater although conjunctive use schemes are also widespread. Overall the available groundwater resources within the catchment are under utilised. Even weaker groundwater occurrence areas can often provide more than 25 litres per person per day. Generally the groundwater quality is good, satisfies the DWAF water quality guidelines and is suitable for domestic and agricultural supply.(Ref.2)

The Olifants Water Management Area:
The groundwater occurrence in The Olifants Water Management Area is controlled by the prevailing lithology. The high groundwater yields in the area are associated with the weathered pockets in the hard rocks which underlie the area and the dolomites. The highest groundwater yields are associated with the dolomite aquifer. Groundwater is extensively used for rural water supplies and stockwatering in the area. (Ref.3)
  References                                      

Ref 1: Department of Water Affairs and Forestry, South Africa. 2004. Internal Strategic Perspective: Limpopo Water Management Area : Prepared by Goba Moahloli Keeve Steyn (Pty) Ltd, in association with Tlou & Matji (Pty) Ltd and Golder Associates (Pty) Ltd. on behalf of the Directorate: National Water Resource Planning. Report No. P WMA 01/000/00/0304.

Ref.2. Department of Water Affairs and Forestry, South Africa. 2004. Luvuvhu/Letaba Water Management Area: Internal Strategic Perspective. Prepared by Goba Moahloli Keeve Steyn (Pty) Ltd in association with Tlou and Matji, Golder Associates Africa and BKS on behalf of the Directorate: National Water Resource Planning. DWAF Report No. P WMA 02/000/00/0304. 

Ref.3. Department of Water Affairs and Forestry, South Africa. 2004. Olifants Water Management Area: Internal Strategic Perspective. Prepared by GMKS, Tlou and Matji and WMB on behalf of the Directorate: National Water Resource Planning. DWAF Report No P WMA 04/000/00/0304 .

Ref.4. Department of Water Affairs and Forestry, South Africa. 2004. Crocodile (West) and Marico Water Management Area: Internal Strategic Perspective of the Marico-Upper Molopo & Upper Ngotwane catchments. Prepared by Goba Moahloli Keeve Steyn in association with Golder and Associates and Tlou and Matji (Pty) Ltd. DWAF Report No. P WMA 03/000/00/0404

Ref.5. Department of Water Affairs and Forestry, South Africa. 2004. Crocodile River (West) and Marico Water Management Area: Internal Strategic Perspective of the Crocodile River (West) catchment : Prepared by Goba Moahloli Keeve Steyn (Pty) Ltd, Tlou & Matji (Pty) Ltd and Golder Associates (Pty) Ltd, on behalf of the Directorate: National Water Resource Planning. DWAF Report No. 03/000/00/0303.

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