基于EFDC模型的河道型水库藻类生长对流域污染负荷削减的响应——以广东长潭水库为例

将环境(EFDC)模型应用于广东梅州的河道型水库——长潭水库,经过模型的验证,建立长潭水库水生态数学模型,模拟出水库在现状污染负荷下的藻类生长情况,以叶绿素a浓度为指标,研究水库在丰水年与枯水年富营养化改善程度对不同流域污染削减方案的响应关系.结果表明:现状污染负荷削减10%,在丰水年库尾、库中和库首点位的叶绿素a平均浓度分别降低13.99%、12.00%和10.35%;枯水年3个代表点位叶绿素a平均浓度分别下降8.42%、5.63%和2.10%.污染削减20%的情况下,丰水年3个代表点位的叶绿素a浓度分别降低26.78%、19.25%和17.04%,枯水年对应的降低幅度分别为11.72%、7.97%和5.12%;库尾地区表现出河道的特征,在污染负荷削减的情况下藻类生长能够受到有效遏制,库首地区则表现出湖泊的特性,枯水年这一特征表现更加突出,污染削减20%的情况下,叶绿素a的平均浓度仅降低5.12%.

Response of algae growth to pollution reduction of drainage basin based on EFDC model for channel reservoirs: A case of Changtan Reservoir, Guangdong Province

The EFDC model has been used to study response of water quality to varying degrees of pollution reduction in Changtan Reservoir. After verification of the model, a water quality model of Changtan Reservoir was built. Algae growth was simulated under the present situation of pollution load. Pollution reduction scenarios based on two hydrologic years were simulated using the water quality model. The results indicated that overmuch nutrient could lead to eutrophication even in wet years. Under 10% reduction of pollution load, average chlorophyll-a concentrations in three areas (reservoir tail, middle and head areas) decreased by 13.99%, 12.00% and 10.35% in wet year and by 8.42%, 5.63% and 2.10% in dry year, respectively. Under the condition of pollution reduced by 20%, chlorophyll-a concentrations in three areas decreased by 26.78%, 19.25% and 17.04% in wet year and by 11.72%, 7.97% and 5.12% in dry year, respectively. The water in the reservoir tail area behaved flowing-water similar to rivers, while the water in the reservoir head area also behaved still-water similar to lakes, which has been more dramatic in dry year and the average chlorophyll-a concentration decreased by 5.12%.