Study on Available Water Amount of Urban River as Cooling Water from the Viewpoint of Influence on Water Quality and Urban Climate

(1)通过实地考察和文献调查，明确了大阪市大川县、竹井川县和道成川县水系的水温、水质和水生生物现状，确定了该水系的环境承载能力。(2)验证了二维流管模型只适用于温差浮力较小的天然河流的水温和水质预测。MIM和SIMPLE算法可用于预测家庭供热和制冷厂的热排放物的热污染区域。通过对大川与内亚河交界处附近水温、溶解氧的实测数据与模拟结果的对比，验证了SIMPLE计算程序的高精度。为了确定水系的环境承载能力，对三维热污染区域进行预测是非常重要的。(3)考虑到对当地水生生物的破坏，确定了大川、竹原和藤川三个水系的环境承载能力。将水生生物的损害程度分为三类，即可忽略损害程度、轻微损害程度和严重损害程度。讨论了河水作为生活供热和制冷厂冷却水的可利用量。

(1) Present condition of water temperature, water quality and aquatic life of Okawa, Tosaborigawa and Dojimagawa water system in Osaka city was clarified by field and literature surveys to determine the environmental carrying capacity of the water system.(2) The authors verified that two-dimensional stream tube model was available to predict water temperature and quality of natural river only where buoyant force caused by temperature difference is small. MIM and SIMPLE algorithms were useful to predict thermally polluted domain by thermal effluents from domestic heating and cooling plant. The high accuracy of SIMPLE computation code was verified by comparison between simulation results and measurement data of water temperature and DO near the junction of Okawa and Neya river. To determine the environmental carrying capacity of water system, it is important to predict three dimensional thermally polluted domain.(3) The authors determined the environmental carrying capacity of Okawa, Tosaborigawa and Dojimagawa water system in consideration of the damage to the local aquatic life. The degree of the damage to the aquatic life was classified to three categories.that is, the level of negligible damage, of slight damage and of severe damage to aquatic life. The available amount of river water as cooling water for domestic heating and cooling plant was discussed for each category.