Discharge analysis for a system approach to river basin development with Subak irrigation schemes as a culture heritage in Bali

Paddy terraces in Baliare important cultural landscapes.  Traditionally, the flow within a river basin has been managed using a traditional technology called Subak irrigation.  These schemes are based on the cropping patterns and indigenous water management, which are organized by the respective Subak associations.  Unfortunately, this traditional technology is facing challenges: water shortage and competition with other water users.  In order to sustain agriculture production of Subak irrigation schemes in the Yeh Ho River Basin, the available discharge in Yeh Ho River was analyzed in this study in light of the supply to the Subak irrigation schemes within the river basin.  By using the Weibull formula, the historic supply data of several diversion weirs were analyzed independently.  Based on this analysis it was possible to determine the water balance of the Subak irrigation schemes behind each diversion weir.  Therefore a system approach was developed based on the managed flows within the river basin and the characteristics of the Subak irrigation schemes.  The conclusion is that the discharge in the river will remain the most important factor to sustain the characteristic paddy terraces of these Subak irrigation schemes

Enhancing the Economic Value of Large Investments in Sustainable Drainage Systems (SuDS) through Inclusion of Ecosystems Services Benefits

Although Sustainable Drainage Systems (SuDS) are used in cities across the world as effective flood adaptation responses, their economic viability has frequently been questioned. Inclusion of the monetary value of ecosystem services (ES) provided by SuDS can increase the rate of return on investments made. Hence, this paper aims at reviewing the enhancement of the economic value of large-scale investments in SuDS through inclusion of ecosystem services. This study focuses on the flood reduction capacity and the ES benefits of green roofs and rain barrels in the combined sewerage network of Montevideo Municipality in Uruguay. The methodology comprises a cost–benefit analysis—with and without monetised ES provided by SuDS—of two drainage network configurations comprising: (i) SuDS; and (ii) SuDS and detention storage. The optimal drainage design for both these drainage configurations have been determined using SWMM-EA, a tool which uses multi-objective optimisation based evolutionary algorithm (EA) and the storm water management model (SWMM). In both design configurations, total benefits comprising both flood reduction and ES benefits are always higher than their costs. The use of storage along with SuDS provides greater benefits with a larger reduction in flooding, and thus is more cost-effective than using SuDS alone. The results show that, for both of the drainage configurations, the larger investments are not beneficial unless ES benefits are taken into account. Hence, it can be concluded that the inclusion of ES benefits is necessary to justify large-scale investments in SuDS

Why indigenous water systems are declining and how to revive them : A rough set analysis

For many centuries, rainwater harvesting (RWH) was the main source of water in many ancient countries. However, over the last four decades, its use has been declining steadily. RWH structures fell into disrepair and were abandoned or were only occasionally used. Taking Sana'a Basin in Yemen as a case study, we examined the underlying factors for the decline and explored ways to reverse it. We interviewed 100 farmers and 65 experts and visited 22 RWH systems, both abandoned and still in use. We used rough set analysis to analyze RWH systems data. The overall results showed that the government plays a crucial role in the operational status of the RWH systems. However, the government's rhetoric on the importance of investing in traditional RWH, very few projects were actually implemented or maintained. In contrast, access to groundwater was heavily promoted making it the preferred water source. However, the water table became depleted and there was a dependency on diesel. Other socioeconomic factors including ownership, limited capacity of RWH systems, the availability of imported food, and rural-urban migration were other secondary reasons for abandonment. Without a shift in government support from groundwater to rainwater harvesting, this long-term decline is likely to continue

A Graduate-Level Field Course in Irrigation and Agricultural Water Management for an Immersive Learning Experience

Effective irrigation and agricultural water management (IAWM) is critical for food security and water security. A key requirement in designing, implementing and operation of IWM is the necessary knowledge and capacity on the farm, in the service industry and within the supply chain. Educational opportunities that not only teach the relevant principles of irrigated agriculture, but also the necessary applied skills are essential. An Irrigation Field Course was initiated by the IHE Delft Institute for Water Education (IHE Delft) and was later developed as a joint field course with IHE Delft, the University of Nebraska-Lincoln (UNL), and the Daugherty Water for Food Global Institute (DWFI). The field course was designed as a two-week course, an immersive experience. The field course was a combination of hands-on laboratory exercises (both lab and field), brief lectures to prepare students for the labs, data analysis, lab reports, and tours. Laboratory topics included surface, sprinkler, and drip irrigation systems; flow in pipelines and open channels; and irrigation well hydraulics. Tours addressed broader topics including IAWM extension programs, technology for irrigation management, manufacturing, water resources management, and impacts on ecosystems. One of the benefits of the field course is that it provides a vantage point from which a student gains a clearer systems perspective of irrigated agriculture, whether their home country is in an irrigation development phase or a water conservation phase. Students often use the data collection skills from the field course in their graduate research projects. A survey was conducted to assess which components of the course were most helpful to the students, and to compare the format of the field course to a typical semester-long course. Students indicated that the immersive two-week experience, with hands-on learning and tours providing a systems perspective, were particularly helpful (60% “strongly agree”) compared to a lecture-based irrigation course