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The Grand Ethiopian Renaissance Dam (GERD) filling and operation is a highly sensitive issue for Egypt and Sudan. A recently accepted manuscript by Heggy et al (2021 Environ. Res. Lett. 16 074022) assessed the water deficit for Egypt based on different scenarios for the first filling of GERD lake and estimated 31 billion cubic meters per year under a 3 year filling scenario. We would like to present grossly mischaracterized assumptions, inaccurate data, and controversial conclusions found in this accepted manuscript through this rebuttal. Although the accepted manuscript does not include any new analysis of the River Nile Hydrology, the results of previous substantive studies were misinterpreted or ignored. Moreover, we have serious concerns about the basic hydrological assumptions that are the basis for the economic impacts and the potential loss of the Egyptian agricultural lands. The main methodological flaws of concerns are (a) how the deficit is calculated, losses from GERD, especially the evaporation losses that contradicts several previous studies (e.g. Wheeler et al 2016 Water Int. 41 611–34; Eldardiry and Hossain 2020 J. Hydrol. 125708; Wheeler et al 2020 Nat. Commun. 11 1–9); (b) neglecting the normal role of High Aswan Dam (HAD) reservoir and directly linking the deficit of the water budget to an immediate loss of agricultural lands with all other associated exaggerated economic impacts estimates; (c) including highly exaggerated seepage losses from the GERD lake; (d) neglecting the updated situation of Aswan High Dam reservoir levels and the GERD’s infrastructure itself, and (e) quantifying the impacts of potential changes of water level on HAD reservoir on the Nubian aquifer. We herein present a direct fact-checking approach including the studies cited in the accepted manuscript. We believe that this critical comment paper can serve as a basis for defending scientific integrity and contributes to cooperation and peace in the region.

Məqalədə iri su anbarlarında baş verə bilən fövqəladə hallar vaxtı yarılma dalğası və cəbhəsinin parametrlərinin, onların zədələyici effektlərinin, yaşayış məntəqələrinə və digər obyektlərə çatacağı vaxtlarının proqnozlaşdırılması məsələləri həll edilmişdir. Bunun üçün elmi ədəbiyyatda isttifadə olunan hesablama metodikası təkmilləşdirilmişdir. Bu aspektdə hesablama eksperimentləri qaydasından istifadə olunmuşdur, yəni baxılan obyektin müvafiq parametrlərinin ehtimal olunan qiymətləri verilir və lazımi hesablamalar aparılır., В статье решены вопросы прогнозирования параметров волны и фронта прорыва, их негативные эффекты и время прихода к населенным пунктам и другим объектам при возможных чрезвычайных ситуациях в крупных водохранилищах. Для этого усовершенствана вычислительная методика, которая используется в соответствующе научной литературе. В этом аспекте использован способ численных экспериментов, т.е. в рассматриваемом объекте задаются вероятные значения соответствующих параметров и проводятся необходимые расчеты., There are solved questions of forecasting of parameters of a wave and front of break, their negative effects and the time of arrival them to the occupied items and other objects at possible extreme situations in large reservoirs in this thesis. For this purpose the mathematical model is developed. In this aspect the way of numerical experiments is used, i.e. in considered object the probable meanings of the appropriate parameters are set and the necessary caculations are spent., Научные труды, Выпуск 2019.21.2 (1-140) 2021, Pages 42-49

This article examines the effect of water pricing policies on farmers’ water saving behaviors, using original water user group (WUG) data from a reservoir irrigation system in China. The introduction of volumetric water pricing at the group level, to replace area-based pricing, induces institutional change to prevent each member’s overuse of water when the volumetric price levels are moderate. Depending on the initial conditions, the multiple pathways of change lead to new institutional arrangements, with all of them contributing to water savings. However, when the price is set high enough, many farmers exit a WUG for private irrigation. This tendency is associated with an increased probability that the remaining members do not undertake institutional change and that they do not end up saving water. This may be due to the increased management difficulties among the remaining members whose fields are separated by former members who have now opted out for private irrigation across the WUG. As a result, we do not find evidence that the reservoir water is saved at high volumetric price levels.

This paper provides an overview of major groundwater issues for Sub-Saharan Africa, with an assessment of their policy implications in terms of potential development and appropriate management. In terms of construction time, capital outlay and drought resilience, groundwater is the preferred source to meet most water-supply demands, despite hydro geological complexity, natural constraints on water well yields and quality, and institutional weaknesses. The 'new developmental agenda' relates to improving urban water-supply security and expanding irrigated agriculture to meet these challenges many countries need to undertake strategic assessment of their groundwater and prioritize investment on institutional strengthening so as to facilitate appropriately-managed groundwater development. Without effective use of available groundwater resources, improved livelihoods and climate-change adaptation will prove much more difficult to achieve.

Urban water demand is rapidly growing in India due to high growth in urban population and rapid industrialization. Meeting this growing demand is a big challenge for the urban planners in India. Incidentally, urban areas in arid and semi arid regions of India are experiencing rapid growth. As a result, the supplies from local water resources including aquifers are far less than the high and concentrated water demands in most urban areas. Under such situations, the cities have to rely on large reservoirs. The paper argues that urban growth would be jeopardized in absence of water supplies from large reservoirs. The analysis of 302 urban centres shows that as population of cities grow, their reliance on surface water sources also grows. Also, greater the share of surface water in the city water supplies, better the level of water supply. A multiple regression analysis of 190 class I cities and 240 class II towns further supports this finding. In Class I cities, with every unit increase in population, there is a 1.12 unit increase in quantum of water supplies. Whereas in Class II towns, with every increase in population, there is only a 0.40 unit increase in quantum of water supply. This shows greater capacities of large cities to respond to the growing water demands, induced by population growth and urbanization. The future projections of population growth, economic development and future water demands clearly means that the role of large reservoirs in meeting the demand of urban water supply is going to be more critical.

The Copenhagen sewerage system was established in 1857. Thus, in 2007 we celebrate our 150th anniversary. Previous to the establishment there were some years of discussion of the principle – combined vs. separate sewer network. Most of the sewer network we know today was founded 1860-1910. Until 1892 the contents of latrines were still collected and driven to the country for fertilization. The rest of the sewage was lead to the harbour, causing extreme odours and sedimentation of sludge. In the time the water closets were allowed to lead the wastewater to the sewer network, the sewage was collected in new pipes along the harbours, and only during rain there were spills from CSO. In the harbour, public baths were established, but because of the poorer and poorer water quality, the last bath closed in 1952. In the 1990s, a SCADA system was established and real time control introduced. Since then, RTC is an integrated part of managing the sewer network. In the same period, some major projects started with the aim of reducing the CSOs and large storage volumes were established. This resulted in the establishment of a public bath in 2002 followed by yet another in 2003.