Textbook 191-195 Coggle
A Coggle Diagram about inputs = runoff, + evaportion + transpiration + groundwater + loss to other catchments + change in soil/surface storage
, Potentially toxic sediment within Lake Burragorang, of great concern, along with the volume of nutrients entering the dam
, Flat landscapes: weathering, soil formation and erosion are naturally occurring processes that, unless there is further tectonic uplifting the result is a flat landscape.
, The catchments that collect water for the rivers can be viewed as simple input/output models. Inputs are generally precipitation, but may also include water introduced from other catchments or sources.
, Remaining water passes as overland flow or runoff to the river
, Eroded material, nutrients, organic matter and, particularly from some groundwater additions, high levels of salts (depending on nature of rainfall and land management in the catchment).
, Loss of inputs = evaporation (from land, vegetation and water surfaces) & transpiration from growing vegetation.
, Vegetation causes a degree of ponding/ water retention (collection of runoff in depressions where it cannot drain out) over the catchment surface. This impedes the flow of surface water, which helps to increase the infiltration of surface water into the soil.
, Human-induced impacts on runoff: more water can be made available in a catchment by transferring water across its watershed. Water can be harvested from one catchment and diverted to another via pipelines, tunnels and canals (economic reasons).
, The ecology of the Snowy River, for example, has suffered because the majority of its spring flush from melting snow is now directed westwards into the Murray River system. The river now shows the effects of excessive silting. In time, however, the river channels and banks and their vegetation will adjust to the new flow regime.
, Water passed through Artesian beds may be lost from catchment
, Eroded river banks may often be replaced by newly deposited landforms; although the gradients of the rivers will steadily be reduced.
, The biophysical environment will also generate naturally occuring nutrients, both from the soil and biotic material (from plants and animals). Despite this, river systems find a balance between these inputs (that is, the river ecosystems) and the outputs.
, Human-induced impacts on sediment and nutrient yield: Sediment yield rises following disturbance of the soil surface, particularly if the protective vegetation is removed and the runoff is increased. Faster sheet-water flows will ensure that more sediment flows into rivers. Land that is used more intensively with fertilizers , the greater the chance of higher nutrient loads reaching river systems also rises.
, Groundwater flows (water that infiltrates the ground surface and is not taken up by vegetation pass through the river .
, Vegetation: inercepts rainfall, effectively protecting the soil surface from more intense precipitation. It's other role is to act as a barrier to overland flow by:
- reducing velocity of runoff and thus surface erosion.
- causing ponding, which increases the time in which infiltration can occur.
- permeable layer of organic material.
- ideal habitat for soil fauna, assisting also with the movement of water into the soil (such as earthworms, in particular, establishing a tunnel network, improving infiltration).
- statistic show that higher infiltration rates are evident in well-vegetated pasture paddocks.
, Soil types, gradients and human activities affect runoff & infiltration
, Cultivating or ploughing fields does not increase infiltration, rather it increases runoff and the potential for erosion. Hard surfaces of urban areas greatly increase runoff. Intensively urbanised areas will have great difficulty in coping with the higher runoff yields.
, Some of the water that infiltrates into the soil seeps into aquifers, where it is stored as groundwater. Approximately 90% of sources have water that is too saline (salty) for human consumption and not fit for irrigation of salt-sensitive crops. Reports of pesticides, have found their way into aquifers. This is a matter of serious concern due to no-flush mechanisms to dilute concentrations
and Increase in sediment yield will lead to siltation. It will also increase the turbidity, or cloudiness, of the river and the level of nutrients in the water. Breeding grounds for fish become limited due to alterations of the river in regards to water quality and temperature, regulation of flows etc. Unsustainable use of important water sources will have devastating effect on the environment and communities that rely on bore water. Example of this: bores in central Australia.