From the IWA journals Water Science & Technology and Water Policy:
Forging linkages: How to scale up urban projects from below
Cities want to recycle water and harvest stormwater, yet few grasp the complex planning, sanctioning, and coordination efforts required. Casey Furlong, Saman De Silva, and Lachlan Guthrie investigated eight “integrated urban water management” (IUWM) projects in Melbourne, Australia and found most emerged from below, at sub-city scales. But without strategic coordination they lingered in urban limbo without approval. Why? Regulators and planners failed to communicate with each other or agree on how to evaluate financial viability. To fix this, they propose “a multi-tier water planning system,” clear “division of decision making responsibilities,” and “consistent frameworks, methods, and objectives at the metro scale.”
Optimising software adapts systems to complex change
No water professional is omniscient, able to track every little shifting input that occurs. So how do we adapt our complex water supply and wastewater disposal systems to rapid demographic, climatic and socioeconomic change? Silja Baron, Jannis Hoek, Inka Kaufmann Alves and Sabine Herz offer a “comprehensive scenario management approach”. An innovative software-based system helps identify in advance the emerging drivers–spatial, natural, engineered–that influence “infrastructures of water supply, wastewater and energy in rural areas.” The authors illustrate calculations of various drivers for a model municipality. By integrating scenarios, they show how to optimise strategies, with impacts on the existing fee system.
Urban water deficits: How much can IWRM help?
Shimla City, capital of Himachal Pradesh, India, is increasingly thirsty. In 25 years it could suffer a nearly sixty million litres per day water deficit, caught between rising demand and limited capacity. How can it close that gap? To find out, Sham Kumar Sharma, M. L. Kansal, and Aditya Tyagi assessed the ungauged Ashwani, Nauti, Giri and Pabbar watersheds. Using remote sensing techniques and geographic information system hydrological models, they found that on average, a metre of rainfall translated into 34 percent runoff, 8 percent groundwater recharge and 58 percent lost through evapotranspiration. Researchers validated results of the water balance through observation, simulation, and measurement of inflow for the Giri River, and established “that existing sources are not sustainable” without “augmentation, coupled with rainwater harvesting and wastewater reuse”.
Desalination for cities: Who ranks on top, and why?
In 1903, Australia built the world’s first land-based desalination plant. But who dominates the desal market today, and why? To find out, Jadwiga R. Ziolkowska compares and evaluates major desalination leaders–United States, Saudi Arabia, Israel, Australia, and China–highlighting their similarities and differences, while depicting “a comprehensive picture of developments, trends and experiences in desalination at the global scale.” Establishing any desalination plant is a complex and multifaceted process. Success depends on managing capital and operational costs, production capacity, water salinity, geographical location and socio-economic and environmental conditions. Country-specific comparisons emphasise the vital importance of regional planning for the long term.
Performance model de-risks cost of urban flood mitigation
Gonbad-e-Kavus, a small city in the north of Iran, had a stormwater problem. Models showed the best outcomes arose from low-impact development: layout of retention ponds that reduce surcharge from the manholes underlying a set of storm event loads. But budget austerity limited the ability to do everything. To help resolve conflicting goals of performance and finance, Farhad Hooshyaripor and Jafar Yazdi developed a simulation- optimisation model for urban flood mitigation. They introduced a new “investment priority index” (IPI), which helps decision makers reduce the risks of surcharging over the network, by prioritising the selection, depth and location of ponds.
