C. Siderius

Interrelationships between hydrology and ecology in fire degraded tropical peat swamp forests

Interrelationships between hydrology and ecology are established for the Air Hitam Laut watershed in Jambi Province, Sumatra, Indonesia. The developed relational diagram shows how modelled regional groundwater levels and flooding patterns are related to the occurrence of different vegetation types in this endangered peatland watershed. In dry conditions when groundwater levels are deeper than 1 m below soil surface, fire disasters are unavoidable. When areas susceptible to fire actually burn and both vegetation and peat disappear, the total inundated area will expand with a factor five. In wet conditions with groundwater levels of more than 1 m above soil surface for a prolonged period of time, flooding creates lakes where no plant species can regrow. In the intermediate range, rehabilitation of different plant species is promising and is related to the actual hydrological regime.

Regional projections of North Indian climate for adaptation studies

Adaptation is increasingly important for regions around the world where large changes in climate could have an impact on populations and industry. The Brahmaputra-Ganges catchments have a large population, a main industry of agriculture and a growing hydro-power industry, making the region susceptible to changes in the Indian Summer Monsoon, annually the main water source. The HighNoon project has completed four regional climate model simulations for India and the Himalaya at high resolution (25km) from 1960 to 2100 to provide an ensemble of simulations for the region. In this paper we have assessed the ensemble for these catchments, comparing the simulations with observations, to give credence that the simulations provide a realistic representation of atmospheric processes and therefore future climate. We have illustrated how these simulations could be used to provide information on potential future climate impacts and therefore aid decision-making using climatology and threshold analysis. The ensemble analysis shows an increase in temperature between the baseline (1970-2000) and the 2050s (2040-2070) of between 2 and 4°C and an increase in the number of days with maximum temperatures above 28°C and 35°C. There is less certainty for precipitation and runoff which show considerable variability, even in this relatively small ensemble, spanning zero. The HighNoon ensemble is the most complete data for the region providing useful information on a wide range of variables for the regional climate of the Brahmaputra-Ganges region, however there are processes not yet included in the models that could have an impact on the simulations of future climate. We have discussed these processes and show that the range from the HighNoon ensemble is similar in magnitude to potential changes in projections where these processes are included. Therefore strategies for adaptation must be robust and flexible allowing for advances in the science and natural environmental changes.

Snowmelt contributions to discharge of the Ganges

Himalayan headwaters supply large quantities of runoff derived from snowmelt and monsoon rainfall to the Ganges River. Actual snowmelt contribution to discharge in the Ganges remains conjectural under both present and future climatic conditions. As snowmelt is likely to be perturbed through climatic warming, four hydrological models, VIC, JULES, LPJmL and SWAT, appropriate for coupling with regional climate models, were used to provide a baseline estimate of snowmelt contribution to flow at seasonal and annual timescales. The models constrain estimates of snowmelt contributions to between 1% and 5% of overall basin runoff. Snowmelt is, however, significant in spring months, a period in which other sources of runoff are scarce.

Climate change and waterborne diarrhoea in northern India: Impacts and adaptation strategies

Although several studies show the vulnerability of human health to climate change, a clear comprehensive quantification of the increased health risks attributable to climate change is lacking. Even more complicated are assessments of adaptation measures for this sector. We discuss the impact of climate change on diarrhoea as a representative of a waterborne infectious disease affecting human health in the Ganges basin of northern India. A conceptual framework is presented for climate exposure response relationships based on studies from different countries, as empirical studies and appropriate epidemiological data sets for India are lacking. Four climate variables are included: temperature, increased/extreme precipitation, decreased precipitation/droughts and relative humidity. Applying the conceptual framework to the latest regional climate projections for northern India shows increases between present and future (2040s), varying spatially from no change to an increase of 21% in diarrhoea incidences, with 13.1% increase on average for the Ganges basin. We discuss three types of measures against diarrhoeal disease: reactive actions, preventive actions and national policy options. Preventive actions have the potential to counterbalance this expected increase. However, given the limited progress in reducing incidences over the past decade consorted actions and effective implementation and integration of existing policies are needed.

Tropical Peatland water management modelling of the Air Hitam Laut catchment in Indonesia

Abstract Human induced land use change and associated fire alter profoundly the hydrology of tropical peatlands and thus affect the functioning of entire river catchments. The hydrological model SIMGRO was used to calculate the effects of drainage on peat water levels, peat surface morphology and river flows within the Air Hitam Laut catchment in Jambi Province, Sumatra, Indonesia. Model outcomes were calibrated and validated using groundwater levels monitored at several sites, discharges measured in the Air Hitam Laut River and flooding patterns derived from remotely sensed Radar images. The validated model was used to predict consequences of three possible scenarios: (i) expansion of oil palm plantations upstream, (ii) expansion of agriculture downstream and (iii) continuing fire damage. Oil palm plantation development results in changes to the drainage pattern of the catchment and reduces its natural extent. Lowered river discharge will have a detrimental affect upon the sustainability of Berbak National Park in the centre of the catchment and reduce prospects for agriculture and fisheries in the coastal zone. Expansion of agriculture downstream causes peat subsidence, resulting in exposure of underlying, acid sulphate soils and intrusion of saline sea water. Continuing fires will increase considerably the area of permanently flooded land and thus constrain peatland restoration options. For peatland restoration to be successful hydrological management must be accompanied by economic measures to improve the livelihoods of local people and by effective law enforcement.

Adaptation to changing water resource availability in Northern India with respect to Himalayan Glacier retreat and changing monsoons using participatory approaches

Changes in rainfall patterns and temperatures are likely to affect water resources in India. Also, changes in the extreme events will have direct implications on life and property. Adapting to the adverse effects of climate change becomes critical to avoid huge material and immaterial damages. This paper discusses the use of a multi-level and participatory approach to develop adaptation options to deal with climate related risks in a manner that contributes to stakeholder engagement, understanding of the risks, identification of the adaptation responses as well as its prioritization for risk reduction. It highlights the importance of involving stakeholders from multiple levels as each level corresponds with different priorities in adaptation options.

Flexible Strategies for Coping with Rainfall Variability: Seasonal Adjustments in Cropped Area in the Ganges Basin.

One of the main manifestations of climate change will be increased rainfall variability. How to deal with this in agriculture will be a major societal challenge. In this paper we explore flexibility in land use, through deliberate seasonal adjustments in cropped area, as a specific strategy for coping with rainfall variability. Such adjustments are not incorporated in hydro-meteorological crop models commonly used for food security analyses. Our paper contributes to the literature by making a comprehensive model assessment of inter-annual variability in crop production, including both variations in crop yield and cropped area. The Ganges basin is used as a case study. First, we assessed the contribution of cropped area variability to overall variability in rice and wheat production by applying hierarchical partitioning on time-series of agricultural statistics. We then introduced cropped area as an endogenous decision variable in a hydro-economic optimization model (WaterWise), coupled to a hydrology-vegetation model (LPJmL), and analyzed to what extent its performance in the estimation of inter-annual variability in crop production improved. From the statistics, we found that in the period 1999–2009 seasonal adjustment in cropped area can explain almost 50% of variability in wheat production and 40% of variability in rice production in the Indian part of the Ganges basin. Our improved model was well capable of mimicking existing variability at different spatial aggregation levels, especially for wheat. The value of flexibility, i.e. the foregone costs of choosing not to crop in years when water is scarce, was quantified at 4% of gross margin of wheat in the Indian part of the Ganges basin and as high as 34% of gross margin of wheat in the drought-prone state of Rajasthan. We argue that flexibility in land use is an important coping strategy to rainfall variability in water stressed regions.

Hydrological Response and Complex Impact Pathways of the 2015/2016 El Niño in Eastern and Southern Africa

The 2015/2016 El Nino has been classified as one of the three most severe on record. El Nino teleconnections are commonly associated with droughts in southern Africa and high precipitation in eastern Africa. Despite their relatively frequent occurrence, evidence for their hydrological effects and impacts beyond agriculture is limited. We examine the hydrological response and impact pathways of the 2015/2016 El Nino in eastern and southern Africa, focusing on Botswana, Kenya, and Zambia. We use in situ and remotely sensed time series of precipitation, river flow, and lake levels complemented by qualitative insights from interviews with key organizations in each country about awareness, impacts, and responses. Our results show that drought conditions prevailed in large parts of southern Africa, reducing runoff and contributing to unusually low lake levels in Botswana and Zambia. Key informants characterized this El Nino through record high temperatures and water supply disruption in Botswana and through hydroelectric load shedding in Zambia. Warnings of flood risk in Kenya were pronounced, but the El Nino teleconnection did not materialize as expected in 2015/2016. Extreme precipitation was limited and caused localized impacts. The hydrological impacts in southern Africa were severe and complex, strongly exacerbated by dry antecedent conditions, recent changes in exposure and sensitivity and management decisions. Improved understanding of hydrological responses and the complexity of differing impact pathways can support design of more adaptive, region-specific management strategies.