3 Case studies

3.1 Sustainable Agriculture

3.1.1 Salinity management under reduced water availability

Increased evapotranspiration and potentially reduced rainfall under climate change can lead to reduced flow, which in turn leads to increased river salinity and reduced water availability. Under increased evapotranspiration and reduced rainfall, additional crop water requirements must be met via irrigation. However, increased river salinity means that more irrigation water is needed to manage soil salinity (via leaching) and maintain crop yields. Because the additional irrigation water may not be available, the application of limited, saline irrigation water will reduce crop yields and increase soil salinity. This case study will explore how irrigators can manage soil salinity and maintain sufficient crop yield under reduced water availability and more saline irrigation water. For this case study, the Murraylands and Riverland Landscape Board will be the main industry partner and lead end user.

3.1.2 Managing permanent plantings under climate change - viticulture

Managing permanent plantings (e.g. grape vines, almond trees) under climate variability and change is challenging. Unlike annual crops, permanent plantings can not be removed or changed during drought. Furthermore, economic conditions and historic investments can make changing crop type difficult. This case study will explore if and how permanent plantings can maintain viability under climate change, without changing crop variety. The Lower Murray wine industry will be used as a case study, with the Murraylands and Riverland Landscape Board will be the main industry partner and lead end user.

3.2 Environmental flows and water use

3.2.1 Managing fish refugia and consumptive use in ephemeral catchments

In ephemeral catchments, fish refugia provide crucial habitat for native fish population during the dry season. In these catchments, high flows during the wet season are also important for maintaining water quality and fish health. However, local agricultural industries rely on storing water (typically via farm dams) to irrigate crops during the dry season. And, aside from agricultural uses, many private land holders also maintain farm dams as a source of stock and domestic water. These farm dams, whether agricultural or private, impact the natural flow regime that sustains the native fish population. This case study will explore the potential impacts of climate change on environmental flows and consumptive users of water in the Marne Saunders Prescribed Water Resource Area (an ephemeral catchment in the Lower Murray). Understanding the effects of farm dams on environmental flows will be important in communicating the risks that climate change is having on both water reliability for local agriculture and the fish population. The Murraylands and Riverland Landscape Board will be the main industry partner and lead end user for this case study.

3.3 Water availability and quality

3.3.1 Maintaining supply and quality under reduced rainfall and increasing bushfires

Many of the major storages in the Murray-Darling Basin are located in heavily forested catchments (e.g. Dartmouth Dam). These catchments have experienced significant bushfires in the past, which in turn impacts catchment yield (via reduced post-fire inflows) and water quality (via increased post-fire sediment load). Furthermore, regions in the southern Murray-Darling Basin are expected to experience reductions in cool season rainfall. Extreme bushfire risk coupled with and reduced cool season rainfall under climate change pose significant risks to water quality and supply. Because these storages supply water to large irrigation areas (e.g. the Mildura Irrigation Area), this case study will examine how the compounding risks of drought and bushfires can be managed to ensure water quality and supply for downstream agriculture. The Northeast Catchment Management Authority will be the main industry partner and lead end user.