Water Conservation in Nepal

Since the last decade, Kathmandu has been immensely crowded by many populations migrating from different places. One of the significant issues in Kathmandu valley today is water management. Nepal is considered the second most prosperous country for water in the world. Despite this, 8.4% of the population of Nepal (2015) do not have access to safe drinking water. Nepal has a high annual rainfall of 1200 millimeters but still faces substantial challenges in ensuring water security. The primary purpose of the new design for the Sport and Recreation Centre project is to conserve the water by reuse, recycling, and systematic utilization of water to create a sustainable water-efficient building and site. The research literature indicates the feasible way to fulfil water needs is by using rainwater harvesting systems in the center. Nepal historically has had rajkulos, canals, human-made ponds and sunken water conduits which are among the oldest techniques of maintaining the water supply. In the Sport and Recreation Centre, historic design techniques have been combined with rain gardens, ponds for groundwater recharge, pervious pavements, and grate inlets to manage the stormwater on the site. Also, treating the greywater through the Reed Bed Treatment System can help and conserve water for the site and project. In the landscape design, specific native plants will be used that conserve water. The buildings will have low flush and composting toilets, sensor taps, rainwater collections, and use. Overall, with the conservation of water on the site and creating a water-saving building design, this can be one of the most effective ways to promote other public buildings to do the same. The people can have adequate residential drinking water. This can help to reduce the scarcity of water in society and teach us to use rainwater and greywater more efficiently in all future new projects.

Rain garden infiltration rate modeling using gradient boosting machine and deep learning techniques

Rain garden are effective in reducing storm water runoff, whose efficiency depends upon several parameters such as soil type, vegetation and metrological factors. Evaluation of rain gardens has been done by various researchers. However, knowledge for sound design of rain gardens is still very limited, particularly the accurate modeling of infiltration rate and how much it differs from infiltration of natural ground surface. The present study uses experimentally observed infiltration rate of rain gardens with different types of vegetation (grass, candytuft, marigold and daisy with different plant densities) and flow conditions. After that, modeling has been done by the popular infiltration model i.e. Philip's model (which is valid for natural ground surface) and soft computing tools viz. Gradient Boosting Machine (GBM) and Deep Learning (DL). Results suggest a promising performance (in terms of CC, RMSE, MAE, MSE and NSE) by GBM and DL in comparison to the relation proposed by Philip's model (1957). Most of the values predicted by both GBM and DL are within scatter limits of ±5%, whereas the values by Philips model are within the range of ±25% error lines and even outside. GBM performs better than DL as the values of the correlation coefficients and Nash-Sutcliffe model efficiency (NSE) coefficient are the highest and the root mean square error is the lowest. The results of the study will be useful in selection of plant type and their density of the rain garden in the urban area.

Măsuri de întărire a capacității de adaptare la schimbările climatice a ecosistemelor acvatice

The current article presents a bibliographic overview of green infrastructures and their role in strengthening the adaptive capacity of aquatic ecosystems to the adverse effects of climate change (high temperatures, heavy rains, droughts). Different types of ecological infrastructures are presented: forest buffer strips, rain gardens, permeable pavement, drainage ditches; bioengineering structures for bank stabilization. Also the functions performed by green infrastructures to maintain ecosystem services were presented: mitigating the effects of floods, stabilizing banks, preventing landslides and water caused erosion, stormwater management, reducing the load of pollutants. For the implementation of this approach in the hydrographic basin of Dniester River or the Prut River a more detailed study is necessary on the state of habitats, identification of hotspot areas of aquatic biodiversity, particularly those species important for maintaining of ecosystem functions, highlighting of the areas at high risk of floods or erosion.

Developing Green Infrastructure Strategies Based on the Analysis of Sewer System Critical Components

Flooding has presented a significant risk for urban areas around the world. Road inundation is one of the severe consequences leading to traffic issues and congestion. Green infrastructure (GI) offers further potential for stormwater management as an environmentally friendly and sustainable solution. However, sewer system behaviour has been overlooked in GI implementation. This study investigates sewer performance by measuring topological connectivity and hydraulic characteristics, and critical components are identified under different design storms. Three retrofit scenarios, including enlarged pipes (grey infrastructure, Grey I), rain gardens (GI), and the combination of enlarged pipes and increased rain gardens (GI + Grey I), are proposed according to the distribution of critical components. The results show that it is feasible to locate the vulnerable parts of the sewer system and GI site allocations based on the critical components that significantly impact the performance of the entire system. While all three scenarios can mitigate inundation, GI and GI + Grey I perform better than pipe enlargement, especially for runoff reduction during long-duration rainfall. Furthermore, the sewer behaviour and retrofit effect are dynamic under different rainfall patterns, leading to diverse combined effects. The discoveries reveal that the adaptation measures should combine with sewer behaviour and local rainfall characteristics to enhance stormwater management.

Blue-green infrastructure as a new trend and an effective tool for water management in urban areas

Blue-green infrastructures (BGI) integrate solutions implemented to enhance water management and landscape values for more climateresilient and livable cities. BGI have created an opportunity to renew the natural structure of water balance in cities through the increase in rainwater retention and enlargement of permeable areas. The review of the literature on BGI development and solutions showed that the most popular BGI elements in terms of urban water quantity and quality were rain gardens, green roofs, vertical greening systems, and permeable pavements. Their structure and effectiveness were presented and reviewed. Despite the consensus between researchers that BGI benefit urban hydrology, differences in runoff decreased (2%-100%) lowering the peak flows (7%-70%) and infiltration (to 60%) or evapotranspiration (19%-84%) were reported. Due to an individual technical structure, each BGI element plays a specific role and there is no universal BGI solution against water-related problems. We inferred that the most effective ones were individually adapted solutions, which prevent from a stressor. The greater variety of solutions in a given area, the more benefits for the urban environment. Our analyses showed that a holistic and co-creative approach to create blue-green networks should be considered in modern water management plans.

Characterization of an area susceptible to floods and inundations in a medium size city in Southern Brazil

The change in precipitation patterns that has occurred over the past decades establishes the discussion about the risks arising from rainfall in urban areas. These risks include floods, inundations and overflow, which are influenced by different conditions. The purpose of this work is to characterize a risk area, susceptible to inundations and floods, in the city of Passo Fundo, in the south of Brazil. In order to propose solutions aimed at mitigating risks for the area, a GIS (Geographic Information System) characterization was applied to prepare thematic maps to identify conditions of infrastructure networks, as well as other constraints of the built environment. The analysis showed that the area, predominantly residential, is currently susceptible to environmental risks, given the proximity to streams, the topography with slopes and impermeable surfaces, despite the existence of rain network infrastructure. Furthermore, the mitigation strategies were proposed, based on the concept of green infrastructure such as the implementation of draining surfaces, rain gardens and a linear park. The data collected in this study will provide subsidies to elaborate the risk maps of the area, deepening the analysis in future studies, assisting the decision making of the public power to prevent and mitigate risks such as floods, according to the identified vulnerability, as well as contribute to Goal 11 - Sustainable cities and communities on the United Nations Agenda 2030.

Measuring the water balance in stormwater control measures

Stormwater control measures (SCMs), also frequently referred to as sustainable urban drainage systems (SUDS), are of growing importance in cities, as part of a global move towards mitigating the impacts of stormwater on receiving environments. They need to be monitored as parts of UDSM systems but require specific and sometimes innovative methods and sensors. This is particularly the case for SCMs such as swales, rain-gardens, bioretention filters, infiltration trenches, green roofs, etc., which have complex and varied configurations and hydrologic behaviour. This chapter deals with measuring the water balance in SCMs by accounting for its various components: inflows, outflows, overflows, storage, infiltration, exfiltration, intrusion, evaporation, and evapotranspiration. It presents a range of suitable methods and tools, indicates key points to consider, and discusses possible difficulties in obtaining accurate monitoring data. Routine monitoring of decentralized and diversified SCMs is still an emerging field for both researchers and practitioners. A significant evolution is therefore expected with its generalization in the next years.