Week 8.docx

Week 8 – Water in climate change and climate change mitigation Our water environments The water budget is a hydrological tool to quantify the flow of water in and out of system. The rate of change of water stored in a given area is balanced by the quantity and rate of water flowing and out of tha...

Week 8 – Water in climate change and climate change mitigation Our water environments The water budget is a hydrological tool to quantify the flow of water in and out of system. The rate of change of water stored in a given area is balanced by the quantity and rate of water flowing and out of that area. P + Qin = ET + ∆S + Qout P = precipitation (rain, snow, etc.) Qin = water flow (discharge) into the watershed ET = quantity of evapotranspiration from soils, surface-water, plants, etc. ∆S = Change in water storage Qout = sum of water flowing out of the watershed Water supply resilience - Resilient water supplies ensure both quantity and quality support all aspects of socio-economic sectors. Water resource resilience - The ability of a system to withstand shocks and continue to function Drought – water shortage Flooding – risk to water supply Heat waves – increased demand Water availability and supply - Water supply depends on the availability and quality of the water. The ground geology and porosity ( the percentage of open space within an unconsolidated sediment or rock) and permeability of soil are the main drivers for the storage of water in a catchment There is a balance between permeability (infiltration) and porosity (storage retention) for aquifers to form –which form natural groundwater reserves. Good aquifers - Groundwater exists where there is porosity i.e. gaps however, how well our groundwater can flow is dependent on permeability i.e. flow ability Gravel, sand and silt make good aquifers - specific yield is high and specific retention is low. Clay makes a good aquitard – specific yield is low and specific retention is high. The role of water in climate change The interaction between water and the major socio-economic sectors impacted by climate change Water vapour is a GHG - It spreads out a lot in the atmosphere (unlike carbon). It can take many forms (cloud, haze, liquid) with different effects. Water vapor roughly accounts for about 60% of the Earth's greenhouse warming effect. Haze - Has a warming effect – solar radiation reaching the ground decreases and the surface heat flux is reduced. Clouds - Cooling effect – providing a reflective surface and increasing surface albedo. Solar radiation is reflected back out (except at night when it has the opposite effect – acts as storage). Hydrological balance - Healthy permeable soil – infiltration (supports vegetation) – percolation - aquifer formation – feeds rivers and streams - more saturated land (more water) - increases evaporation – increases condensation – more rain Drought: Reduced vegetation – lower evapotranspiration – less humidity – reduction in cloud cover sand less rain Less evaporation – less evaporative surface cooling – greater sensible heat flux – creates a warming effect Flood: Bare ground exposure – compaction of ground – reduced infiltration – increased surface runoff OR impermeable surfaces – reduced infiltration – increased surface runoff Creation of floods – reduced water storage – depletion of ground water Rural vs urban hydrograph Response of water resources to climate change Changes in both precipitation and temperature directly impact the water budget -> increased precipitation in N latitudes. E.g. Polar regions are predicted to experience accelerated melting of glaciers – locally and temporality increasing water availability – increased stream flow. Semi-arid areas will experience increased aridity and increased warming because of reductions in reliability of water flows Coastal hinterlands (land that extends towards the coastline) – sea level rise will threaten these regions as well as saline intrusion to water supplies Mountainous regions – high mountains areas are predicted to warm faster than lower elevations - Cold surface temperatures + Increased snow + Increased albedo - Less solar radiation absorbed + Higher surface temperatures +increased temperatures + increased atmospheric water vapor +increases downward longwave radiation Melting of glaciers and snow-caps could increase water security nit also change vegetation and soil and impact large ecosystem services like biodiversity and carbon sequestration Risk sensitive ecosystems – wetlands Highly vulnerable to changes in water flow They provides ecosystem services like filtering, buffering and carbon sequestration Peatlands store 2x more carbon than the worlds forests Over last 100 years half of worlds natural wetlands have been lost High watertable: Lack of oxygen as peat is still covered – anoxic conditions Less microbial activity Organic matter is not degraded Carbon is stored Low watertable: Oxic conditions – water is drained exposing peat layers Activates microbes Organic matter is degraded Carbon is released in water and atmosphere Impacts to water quality: Greater runoff caused greater river loads of heavy metals, salts, coliforms, pathogens, organic matter Reduced risk of eutrophication when nutrients are flushed away by storms Rising temperatures and sea level rise – saline intrusions Increasing temperatures – increased risk of algal blooms and toxins in water Increase evaporation from increasing temperature – less water in lakes and rivers Climate change mitigation and water resources Within the next 30 years demand for water from agriculture could increase by 50 percent, and for urban uses by between 50 percent and 70 percent. We will be faced with having to divide the same amount of water across more components. Methods of mitigation: Water conservation - Implementing water conservation measures such as efficient irrigation systems, reducing water loss in distribution systems, and promoting water-efficient appliances and practices can help reduce water consumption and increase the availability of freshwater resources. Enhancing water storage and management - Investing in water storage infrastructure such as dams and reservoirs can help manage water availability during times of drought or low rainfall. Improving water quality - Addressing pollution sources and improving wastewater treatment can help ensure that freshwater resources remain clean and safe for human consumption and the environment. Promoting sustainable land use practices - Encouraging sustainable land use practices such as reducing deforestation, promoting agroforestry, and promoting sustainable agriculture practices can help maintain healthy ecosystems and ensure the availability of freshwater resources. e.g. Bermuda has no fresh water springs, rivers or lakes so how do humans settle there? Buildings are designed to harvest rainwater through roofs Each house is self-sufficient – there are no water mains on the island Roofs are made from limestone - the white paint reflects UV lights from the sun and helps to purify the water. Sustainable land practises: Reducing erosion and sedimentation - agroforestry, conservation tillage, and cover cropping can help reduce erosion and sedimentation in waterways, improving water quality and reducing the negative impacts of flooding and drought on freshwater systems. Promoting natural water filtration - Sustainable land practices such as riparian buffer zones, wetland restoration, and conservation of natural vegetation can help promote natural water filtration, improving water quality and reducing the need for expensive water treatment infrastructure. Protecting and restoring wetlands - It is designed to replicate the natural processes of a wetland, but is constructed specifically for the purpose of wastewater treatment. Wetlands filter out pollution and allow water to soak into the ground, recharging groundwater supplies. Benefits include: Filter out pollutants -> increase water retention times, Allow water to soak into groundwater -> groundwater recharge, Promote biodiversity, Accumulate and store organic matter in soil, Wetland plants grow at a faster rate than them decompose -> carbon capture, Depending on water levels -> bacterial oxidation can convert DOC into inorganic matter which can be stored by mineralization. Wetlands act as natural carbon sinks, absorbing and storing carbon dioxide, and reducing the amount of greenhouse gases in the atmosphere. Protecting and restoring wetlands can help reduce the impacts of climate change on freshwater systems. Promoting sustainable agriculture practices - Encouraging sustainable land use practices such as reducing deforestation, promoting agroforestry, and promoting sustainable agriculture practices can help maintain healthy ecosystems and ensure the availability of freshwater resources Promoting forest conservation and restoration Expand water availability and supply - The types of water source available to a water company are largely dependent on the environmental characteristics of the region. Reservoirs can provide large-scale water storage. Thames Water rely on surface water more than any other water company – their priority is to increase storage capacity. Demand in the London Water Resource Zone was exceeded 2020 and the deficit is projected to increase by tenfold in 2044 - from 35 to 362 megalitres per day! Building more dams and reservoirs may provide short-term solutions to water shortages, but may also have negative impacts on ecosystems and water quality. e.g. Eutrophication - The enrichment of waters by inorganic plant nutrients, especially nitrogen and phosphorus which results in an increase in primary production. Effects Species diversity often decreases and the dominant biota change Plant and animal biomass increases Turbidity increases Rate of sedimentation increases, shortening the lifespan of the lake. Anoxic conditions develop Problems The water maybe injurious to health The amenity value of the water may decline Increased vegetation may impede water flow and navigation Commercially important species of fish may disappear Treatment of drinking water may be difficult Nature Based Solutions - introduced towards the end of the 2000s by the World Bank (MacKinnon et al.2008). International Union for Conservation of Nature (IUCN) recognises that human well being does not need to come at the expense of nature – biodiversity can itself generate human well-being and economic benefits Features: Broad in scope and definition. Designed to target climate change but also/can address biodiversity conservation, disaster risk reduction, green economy promotion, and further economic growth. 2. “Nature”. The term nature is broad – European Commission lists 310 actions as examples of NBS ranging from: expansion and protection of forests , planting green roofs, carbon storage and storm water retention. Can be distinguished from conventional engineering techniques as being – multifunctional, conserving and adding to the stock of natural capital and being adaptable in order to contribute resilience to a landscape. Bottom up. Governance-based approaches to both the creation and management are embraced. Participatory approaches to co-design, co-creation and co-management are advocated. Action orientated. Policy must be linked to action on the ground. This requires regulatory frameworks, planning systems and economic instrumentation is strong. Under Horizon 2020/ Horizon Europe (European Research and Innovation funding) NBS research must include large scale pilot and demonstration projects to serve as a reference point for upscaling NBS. New Innoveations: Algae Algae can remove as much carbon as all the trees, plants and land combined. E,g, Uk company, Brilliant Planet The technology developed by this company has the potential to sequester 2 billion tonnes of carbon dioxide a year! The process involves pumping sea water which is rich in carbon and nutrients from the ocean in algae aquacultures, located in coastal desert locations -> Morocco Carbon and nutrients in the sea water support the growth of local strains of algae, through a specially developed accelerated growth process. What makes algae really efficient is that it doesn’t need to grow huge support systems e.g. trunks and roots to take in C via photosynthesis. The algae can double in biomass in less than a day. Shade balls: During times of drought reservoirs act as water stores for many communities. Reservoirs are suspectable to large amounts of evaporation -> problematic Amid California’s latest drought (2011-2017) 96 million ‘shade balls’ were deployed on the LA reservoir. These are black plastic balls that cover the surface preventing evaporation.