Insights into the Pollutant Removal Performance of Stormwater Green Infrastructures: A Case Study of Detention Basins and Retention Ponds

The quality of water has deteriorated due to urbanization and the occurrence of urban stormwater runoff. To solve this problem, this study investigated the pollutant reduction effects from the geometric and hydrological factors of green infrastructures (GIs) to more accurately design GI models, and evaluated the factors that are required for such a design. Among several GIs, detention basins and retention ponds were evaluated. This study chose the inflow, outflow, total suspended solids (TSS), total phosphorus (TP), watershed area, GI area (bottom area in detention basins and permanent pool surface area in retention ponds), and GI volume (in both detention basins and retention ponds) for analysis and applied both ordinary least squares (OLS) regression and multiple linear regression (MLR). The geometric factors do not vary within each GI, but there may be a bias due to the number of stormwater events. To solve this problem, three methods that involved randomly extracting data with a certain range and excluding outliers were applied to the models. The accuracies of these OLS and MLR models were analyzed through the percentage bias (PBIAS), Nash-Sutcliffe efficiency (NSE), and RMSE-observations standard deviation ratio (RSR). The results of this study suggest that models which consider the influent concentration combined with the hydrological and GI geometric parameters have better correlations than models that consider only a single parameter.

SUSTAINABLE URBAN PUBLIC PARK LANDSCAPE DESIGN CRITERIA BASED ON COMMUNITY PERCEPTION AND ASPIRATIONS

<p>This article interprets the perception and aspirations of the city community, as a cornerstone of drafting the design criteria of a community-based city park landscape, which is effective and sustainable. Flooding and drought problems in Jakarta and surrounding areas should be resolved in a comprehensive, integrated and sustainable manner. Referring to the Water Sensitive Urban Design (WSUD) which is an innovation in integrated water management, it is recommended to develop the function of detention and retention ponds as part of storm drainage system, replacing conventional system. Development of the city park landscape criteria as the synergies of the RTH function and the detention/retention ponds should be approached in a very careful, avoiding fatal malfunction and harsh rejection of the user community. The best approach should be done through tracing the needs, desires and expectations of the city community as the ‘end user' as well as 'super client' of the city park. Research on the perception and aspirations of the city community on the idea of the development of City Park with the role of retention/retention ponds has been conducted between February to May 2020 in Jabodetabek. <strong></strong></p>

Edukasi Guru SD Kaligawe Semarang sebagai Upaya Peningkatan Partisipasi Masyarakat dalam Pemeliharaan Infrastruktur Pengendali Banjir

Kaligawe merupakan salah satu daerah rawan banjir di Kota Semarang. Kawasan Kaligawe termasuk dalam Sub Sistem Kali Tenggang. Penanganan terhadap banjir di Kaligawe telah dilakukan oleh pemerintah berupa normalisasi sungai dan pembangunan sistem polder sebagai bagian dari sistem drainase. Untuk menjamin keberlanjutan pengelolaan sistem drainase, diperlukan keterlibatan seluruh stakeholders, termasuk partisipasi masyarakat yang bertempat tinggal di dalamnya. Di wilayah Kaligawe, ada beberapa bangunan infrastruktur pengendali banjir seperti kolam retensi, rumah pompa, pintu gerak dan saluran drainase. Bangunan infrastruktur tersebut dapat terganggu fungsinya bila masyarakat tidak peduli, seperti membuang sampah di saluran drainase, merusak kolam retensi, mengambil/mencuri peralatan di rumah pompa dan lain sebagainya. Oleh sebab itu warga di kawasan tersebut perlu mendapatkan edukasi bagaimana hidup di lingkungan sistem polder. Sekolah Dqsar (SD) Kaligawe berada di wilayah Kaligawe, dimana para guru perlu diberikan edukasi agar dapat ikut berpartisipasi dalam pemeliharaan bangunan infrastruktur pengendali banjir. Edukasi yang akan diberikan meliputi pemahaman tentang penyebab dan dampak banjir di Semarang, penanganan banjir dan bangunan infrastruktur pengendali banjir di sekitar sekolah serta mitigasi bencana dan konsep Sekolah Siaga Bencana (SSB). Hasil pre-test terhadap guru, menunjukkan bahwa guru-guru di SD Kaligawe masih banyak yang tidak memahami bangunan pengendali banjir yang ada di sekitar lingkungan kerja mereka. Melalui edukasi yang diberikan dalam penyuluhan, guru-guru bisa memahami peran yang harus dilakukan dalam menjaga keberlangsungan bangunan pengendali banjir. Hasil post-test menunjukkan tingkat pemahaman yang meningkat pada guru-guru terhadap pengendalian banjir di wilayah Kaligawe.Kaligawe is one of the flood areas in the city of Semarang. Kaligawe area is included in the Kali Tenggang Sub-System. The government has handled floods in the area in the form of river normalization and construction of a polder system as part of the drainage system. To ensure the sustainability of the drainage system management, it requires the involvement of all stakeholders, including the participation of the people who live in it. In the Kaligawe area, there are several flood control infrastructure buildings such as retention ponds, pump houses, mobile gates and drainage channels. The function of these infrastructure buildings can be disrupted if the community does not care, such as throwing garbage in the drainage channels, damaging retention ponds, taking / stealing equipment at pump houses and so on. Therefore, residents in the area need to get education on how to live in a polder system environment. SD Kaligawe is located in Kaligawe area, where teachers need education in order to participate in the maintenance of flood control infrastructure. The education that will be provided includes understanding the causes and impacts of floods in Semarang, flood management and building flood control infrastructure as well as disaster mitigation and the concept of Disaster Alert School (SSB). The results of the pre-test conducted in this study showed that many teachers at SD Kaligawe did not understand the flood control buildings that were around their school environment. Through the education provided in counseling, teachers can understand the role that must be played in maintaining the sustainability of flood control buildings. The results of the post test showed an increased level of teachers on understanding of flood control in the Kaligawe area.

Evaluation of nutrient retention and sediment deposition in two urban stormwater retention ponds

Stormwater ponds have been implemented in many municipalities to control urban runoff and retain pollutants, such as nutrients and suspended solids. Two stormwater ponds in Toronto, Ontario were evaluated for their ability to retain nutrients and suspended solids and were also used to investigate mechanisms by which stormwater ponds remove nutrient pollutants, including the importance of deposition and internal loading. Over the entire study period, Hydro Pond East (HEP) retained 1415 mg of total suspended solids (TSS) and MAT retained 1127 mg of TSS. Both Hydro East Pond (HEP) and Mattamy Rouge (MAT) were net exporters of phosphorus (P) over the entire season, with 6.35 mol or 0.20 kg and 53.9 mol or 1.67 kg exported, respectively. HEP had net retention of 2672 mol or 37.4 kg of nitrogen (N) but MAT exported 264 mol or 3.7 kg of nitrogen over the entire study. This study has demonstrated that stormwater ponds have the ability to provide retention of nutrients and TSS, but their function may be enhanced as they may become exporters. However, the amount of nutrients exported was extremely low and may have been driven by the anomalously dry 2016 year in Toronto. Further research should be done on these same ponds to observe how they may perform under an anomalously wet year (e.g. 2017). There is a need for a future model to synthesize the data from literature on stormwater ponds to better understand their function to better help local water managers determine if these ponds are needed and how they may need to enhance their function.

Evaluation of nutrient retention and sediment deposition in two urban stormwater retention ponds

Stormwater ponds have been implemented in many municipalities to control urban runoff and retain pollutants, such as nutrients and suspended solids. Two stormwater ponds in Toronto, Ontario were evaluated for their ability to retain nutrients and suspended solids and were also used to investigate mechanisms by which stormwater ponds remove nutrient pollutants, including the importance of deposition and internal loading. Over the entire study period, Hydro Pond East (HEP) retained 1415 mg of total suspended solids (TSS) and MAT retained 1127 mg of TSS. Both Hydro East Pond (HEP) and Mattamy Rouge (MAT) were net exporters of phosphorus (P) over the entire season, with 6.35 mol or 0.20 kg and 53.9 mol or 1.67 kg exported, respectively. HEP had net retention of 2672 mol or 37.4 kg of nitrogen (N) but MAT exported 264 mol or 3.7 kg of nitrogen over the entire study. This study has demonstrated that stormwater ponds have the ability to provide retention of nutrients and TSS, but their function may be enhanced as they may become exporters. However, the amount of nutrients exported was extremely low and may have been driven by the anomalously dry 2016 year in Toronto. Further research should be done on these same ponds to observe how they may perform under an anomalously wet year (e.g. 2017). There is a need for a future model to synthesize the data from literature on stormwater ponds to better understand their function to better help local water managers determine if these ponds are needed and how they may need to enhance their function.