Measurements of 水的质量
Ben Houston, GroundPoint Engineering
Water quality is determined by a variety of different indicators, including water 温度, the particulates in the water, and the levels of different 营养物质. Keeping all of these factors within a healthy range helps the stream, 以及它周围的土地, 保持健康.
Hydropower can result in changes to water level and flow, potentially impacting four main water quality characteristics:
- 温度
- 营养物质
- 水化学
- 沉积
温度
温度 changes in the stream are perhaps the greatest water quality concern when it comes to installing micro hydropower. Organisms living in the stream are used to a certain 温度 range, and going outside this usual range can alter their biological processes. The two most common ways that 温度 can be affected are by:
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- Raising the height of the dam and increasing the size of the retention area.
- Removing water from the stream at the dam, and returning the water to the stream further downstream. This can cause an increase in water 温度 in the stretch of stream that has lower water flow.
One additional way to help reduce 温度 increases is through reforestation in the riparian zone, which includes the stream banks and floodplain. Planting vegetation with leaves that hang over the stream can help reduce the stream’s exposure to direct sunlight which can lower water 温度s.
营养物质
Hydropower systems do not add or remove 营养物质 to the stream. 然而, nutrient concentrations can be affected if the flow of water down the stream changes. 特别是, nutrient concentrations in any areas where bypass flow is needed to generate power should be monitored. One important consideration for nutrient changes is in areas near known wastewater treatment plant outfalls.
Nutrient levels and 温度 changes are also related, 意思是随着一个人的变化, 它会影响另一个. 例如, if the installation of a micro hydro system causes an increase in water 温度, that could cause an increase in algae and plant growth. This additional algae growth uses more 营养物质 and could then have an effect on 水化学 indicators like dissolved oxygen. These changes affect the stream habitat for other aquatic organisms.
水化学
The existence of a dam alters stream chemistry by changing water depths and the activity of the organisms living there. Examples of important indicators to monitor for resilience and ecosystem health include:
- 溶解氧
- 氮
- 磷
- 温度
- 导电率
- 浊度
- Fecal Indicator Bacteria
- 盐(又名路盐)
沉积
If installed on an existing dam, a hydro-electric project should not impact the sediment supply in a stream. There is no anticipated change in the overall sediment supply moving downstream resulting from a hydropower project. 然而, the construction process can create opportunities for sediment mobilization. Heavy machinery along stream can erode the banks and cause soil to the flow downstream, and any disturbance to the settled sediment behind the dam can affect water quality in the impounded area.
It is also important to remember that dams trap sediment and prevent it from flowing downstream beyond the dam. This means that sediment builds up on the upstream side of the dam over time, filling in the impounded area. Understanding this process for a specific site is important for long term dam operations.
In the 十大外围足彩网站app, the 吟游诗人水实验室‘s community based water quality sampling program has helped to establish baseline water quality conditions that can be used to assess current conditions in the stream.
Other 水的质量 Concerns
Every micro hydropower site is part of the larger stream or river system. Events that happen upstream of a project may affect the water quality of your site. Knowing how your system affects the water quality at your section of the stream can help all involved stakeholders understand any changes to water quality along the stream.
There are other sources of water quality impact that may exist in the watershed that typically have nothing to do with hydropower installation. 然而, they may be important as part of the assessment of long term operation and maintenance of a dam and micro hydropower system, as well as the cumulative environmental impacts along the stream.
