Reservoir water quality
Nutrient concentrations in upstream water will determine the trophic rating of the reservoir. Research indicates that current nutrient levels will likely lead to the eutrophication of the reservoir. Indeed, high levels of nutrient will result in algal blooms which inhibit light from penetrating to deeper dwelling organisms. On top of this, the decomposition of deceased algal blooms consumes high levels of oxygen and thus may lead to hypoxic water conditions. Below is a table indicating the level of nutrient concentration associated with different levels of water quality. Data shows that hypereutrophic conditions occur all along the Tigris with increasing concentration of nutrients downstream of Diyarbakir and of Bismil. Though concentration of nutrients decreases further downstream, results still indicate a hyper-eutrophic state.
The reservoir consists of karstified limestone of the Midyat formation. As was discussed in the erosion and sediment page, this leads to erosion. The rise of the reservoir water level will decrease slope stability, cause changes in the flow regime, surface and groundwater quality and create a micro-climate which holds implications for the fish population and biodiversity. The micro-climate will be a result of lake stratification. Stratification occurs seasonally in lentic aquatic environments due to changes in temperature. In winter the cold water is denser and will sink. Warmer water will remain at the surface of the lake. Additionally, dissolved oxygen will sink to the bottom. As the reservoir will likely be eutrophied - causing hypoxic conditions; this holds implications for the biota that require certain levels of oxygen. Below Table: Demonstrates the trophic states and their corresponding levels of Nitrogen, Phosphorus, Chlorophyll -a, and Secchi depths readings.
|