Dams, through disruption of physiochemical and biological processes, have water and associated environmental impacts that have far reaching social and economic consequences. The impact of each dam is unique. It depends not only on the dam structure and the attributes of local biota but also climatic and geomorphic conditions. Given the number of existing dams (over 45,000 large dams) and the large number that may be built in the near future, it is clear that humankind must live with the environmental and social consequences for many decades to come. This paper provides a review of the consequences for ecosystems and biodiversity resulting directly from the presence of dams on rivers, and of constraints and opportunities for environmental protection. It illustrates that a wide range of both technical and non-technical measures has been developed to ameliorate the negative impacts of dams. It argues that relatively few studies have been conducted to evaluate the success of these measures and that it is widely perceived that many interventions fail, either for technical reasons or as a consequence of a variety of socio-economic constraints. It discusses the constraints to successful implementation and mechanisms for promoting, funding and ensuring compliance. Finally, it contends that there is a need to improve environmental practices in the operation of both existing and new dams.

Trends in rainfall series were investigated at 16 stations in Ghana over the period 1960–2005. Time series were first de-correlated using an effective pre-whitening methodology and then submitted to the resampling-based Mann-Kendall test. Field significances were assessed using the regional average Kendall statistic. Although no significant changes were observed in annual rainfall, the analysis reveals: (a) a reduction in the number of wet season days totalling less than 20 mm of rainfall, between latitudes 6° and 9.5°N; (b) a delay (about 0.5 d year^‐1) in the wet season onset at several locations throughout the country; and (c) a lengthening (about 0.1 d year^‐1) of rainless periods during the wet season in the south and centre of Ghana. All these changes, which remained insignificant at more than half of the individual stations, were found to be regionally significant at the 95% confidence level. The results highlight the importance of evaluating regional significance when investigating climate trends. Editor Z.W. Kundzewicz Citation Lacombe, G., McCartney, M., and Forkuor, G., 2012. Drying climate in Ghana over the period 1960–2005: evidence from the resampling-based Mann-Kendall test at local and regional levels. Hydrological Sciences Journal, 57 (8), 1594–1609.

Ethiopia's policy of large dam construction in the Blue Nile River basin is evaluated by simulating the impact of one downscaled midrange climate change scenario (A1B) on the performance of existing and planned irrigation and hydropower schemes. The simulation finds that by 2100: 1) average basin-wide irrigation demand will increase; 2) annual hydroelectricity generation will be just 60% of potential; and 3) flow at the Ethiopia-Sudan border will be reduced from 1661 m³/s to 1301 m³/s as a consequence of climate change in combination with upstream water resource development. Adaptation to climate change and development must be considered together.

The 2030 Agenda for Sustainable Development, the Sustainable Development Goals (SDGs), are high on the agenda for most countries of the world. In its publication of the SDGs, the UN has provided the goals and target descriptions that, if implemented at a country level, would lead towards a sustainable future. The IAEG (InterAgency Expert Group of the SDGs) was tasked with disseminating indicators and methods to countries that can be used to gather data describing the global progress towards sustainability. However, 2030 Agenda leaves it to countries to adopt the targets with each government setting its own national targets guided by the global level of ambition but taking into account national circumstances. At present, guidance on how to go about this is scant but it is clear that the responsibility is with countries to implement and that it is actions at a country level that will determine the success of the SDGs. Reporting on SDGs by country takes on two forms: i) global reporting using prescribed indicator methods and data; ii) National Voluntary Reviews where a country reports on its own progress in more detail but is also able to present data that are more appropriate for the country. For the latter, countries need to be able to adapt the global indicators to fit national priorities and context, thus the global description of an indicator could be reduced to describe only what is relevant to the country. Countries may also, for the National Voluntary Review, use indicators that are unique to the country but nevertheless contribute to measurement of progress towards the global SDG target. Importantly, for those indicators that relate to the security of natural resources security (e.g., water) indicators, there are no prescribed numerical targets/standards or benchmarks. Rather countries will need to set their own benchmarks or standards against which performance can be evaluated. This paper presents a procedure that would enable a country to describe national targets with associated benchmarks that are appropriate for the country. The procedure builds on precedent set in other countries but in particular on a procedure developed for the setting of Resource Quality Objectives in South Africa. The procedure focusses on those SDG targets that are natural resource-security focused, for example, extent of water-related ecosystems (6.6), desertification (15.3) and so forth, because the selection of indicator methods and benchmarks is based on the location of natural resources, their use and present state and how they fit into national strategies.