Developing a preliminary recharge model of the Nile Basin to help interpret GRACE data

GRACE data provides a new and exciting opportunity to gain a direct and independent measure of water mass variation on a regional scale, but the data must be combined with hydrological modelling to indicate in which part of the water cycle the mass change has occurred. Processing GRACE data through a series of spectral filters indicates a seasonal variation to gravity mass (±0.005 mGal) thought to relate to the downstream movement of water in the catchment, and delayed storage from groundwater, following the wet season in the upper catchment. To help interpret these data a groundwater recharge model was developed for the Nile Catchment using the model ZOODRM (a distributed modelling code for calculating spatial and temporal variations in groundwater recharge). ZOODRM was an appropriate model to use for this work, due to the lower data demands of the model, relative to other groundwater models, the ability of the model to use entirely remotely-sensed input data, and the added functionality of runoff routing. Rainfall (NOAA data) and ET data were sourced from the FEWS NET African Data Dissemination Service. Geological data was sourced from the digital geology map of the world, landuse data from the USGS and the DEM data from ESRI. Initial model results indicate groundwater recharge across the basin of 0-4mma-1, with obvious considerable spatial variability. The results indicate the importance of groundwater in storing rainfall, and releasing it slowly throughout the year in different parts of the catchment. Only by modelling this process can GRACE data be reliably interpreted hydrologically. Despite only a qualitative interpretation of the GRACE data having been achieved within this preliminary study, the work has indicated that the ZOODRM model can be used with entirely remotely-sensed data, and that sufficient data exists for the Nile Basin to construct a plausible recharge model. Future work is now required to properly calibrate the model to enable closer comparison of the Nile GRACE data

Recharge modelling for the West Bank aquifers.

Recharge can take two main forms, direct recharge from rainfall infiltrating the ground or indirect recharge from leakage from wadi beds. The recharge processes operating in the West Bank can be summarised as rainfall recharge, wadi recharge, urban recharge processes and irrigation losses. Rainfall recharge is the predominant form of recharge, whilst wadi recharge, urban and irrigation losses are only minor components. However, these minor components can be locally important. The recharge processes operating in the Wadi Natuf catchment are varied and complex. The four main geological strata through which recharge takes place are: • Jerusalam • Upper Lower Beit Kahil • Lower Beit Kahil • Hebron The main aquifer units are karstic which receive recharge once a wetting threshold is exceeded. This assumption is supported by field observations (Messerschmid, 2003) and a field experiment close to the study area (Lange et al., 2003). Other minor aquifers receive recharge and distribute water laterally to springs. Flow from springs, if not used for water supply or irrigation, can then be routed to other aquifer units or as loss from wadis. High intensity rainfall can produce overland runoff and wadi flow. Flowing wadis loose water to all but the Yatta formation. Recharge can, therefore, occur by two methods, direct infiltration from rainfall and from losses from wadi beds. There are four main recharge processes operating in the aquifers of the West Bank; 1. Direct recharge from rainfall 2. Indirect recharge from wadi losses 3. Recharge from urban water supply and waste water proceses 4. Recharge from irrigation losses The difference between rainfall and potential evaporation, known as effective rainfall, is the main control on direct recharge from rainfall. Rainfall is greatest in the north and west whereas potential evaporation is the highest in the south and east. The greatest potential for rainfall recharge is, therefore, in the north and west. Soil cover also controls the amount of rainfall recharge and is highly variable over the West Bank. In particular, the main soil types have patchy coverage, over only 30-50 % of the ground surface, the rest being bare rock. The patchiness of the soil means that soil moisture is not developed in the same way as for soils with uniform coverage. To determine the rainfall recharge mechanisms operating in the West Bank, a combination of factors such as rainfall, potential evaporation, soil cover, land use, etc need to be assessed. Combining these factors mean that recharge processes based on soil moisture are most likely to be operating in the north-west of the West Bank. Elsewhere, direct recharge will be based on how the soil and rocks combined as single system respond to the balance between rainfall and evaporation (e.g. Lange et al., 2003). Indirect recharge occurs due to wadi flows over the whole of the West Bank. Runoff from intense rainfall events will collect in valley bottoms and create surface water flows. Recharge from wadi beds will form the predominant source of recharge in the south and east of the West Bank, where the climate is more arid. Urban recharge processes reflect leakage from pipes and sewers and increased runoff from paved surfaces, roofs, roads, etc. The enhanced runoff in the urban environment is routed to wadis and enhances flows after rainstorms. This can increase indirect recharge from wadi beds. Losses from irrigation systems can enhance recharge. The main areas for irrigation are the north-west of the West Bank, in the vicinity of Jericho and the Upper Jordan Valley. A significant amount of work has been undertaken on calculating recharge to the aquifers in the West Bank and in the Western Aquifer Basin by measuring discharge and abstraction as a surrogate for recharge. However, most of the estimates rely on empirical relationships between annual rainfall and recharge. Estimates undertaken using an empirical method are not physically based, but nonetheless can be used as a guide to determine whether the recharge calculated by the modelling are realistic. The estimates for the Western Aquifer Basin are around 350 Mm3 a-1 and 800 Mm3 a-1 for the West Bank as a whole. To enable recharge to be calculated using a physical basis over aquifer outcrops, a distributed recharge model has been developed and tested. An existing object-oriented groundwater flow model has been adapted from an existing code. An object-oriented approach was chosen to enable a range of recharge mechanisms to be incorporated easily into the model. Recharge is calculated at a node, which is held on a grid and enables a distributed recharge estimate to be undertaken. Four types of recharge node can be specified; soil moisture balance method, wetting threshold, urban recharge process and irrigation losses. In addition to these mechanisms, runoff routing to wadis and subsequent infiltration is implemented

Tension over equitable allocation of water : estimating renewable groundwater resources beneath the West Bank and Israel

Competition for water resources between Palestine and Israel is an ongoing cause of tension. The Western Aquifer Basin forms a major part of the complex, largely karst, limestone system of the West Bank Mountain Aquifer. The aquifer crops out and is recharged solely in the semi-arid uplands of the West Bank and groundwater flows west beneath Israel to discharge at the Yarqon and Nahal Taninim springs near the Mediterranean coast. Annual recharge to the aquifer is not easy to quantify but lies within the range 270×106 to 455×106 m3 a−1, and current uncertainties do not support definition of a single value of long-term average recharge. The resource is heavily exploited and abstraction is directly controlled and apportioned between Israel and the West Bank by Israel. The key to equitable apportionment is the determination of the long-term average recharge to the basin, which also requires definition of the eastern boundary of the basin to confirm the recharge area. Calculations include empirical formulae and process-based models that are likely to constrain the best estimate provided that there is appropriate, ongoing monitoring. Improved understanding can then be fed back into the model

Summary of results for national scale recharge modelling under conditions of predicted climate change

This report describes the application of the BGS distributed recharge model ZOODRM to produce recharge values (potential recharge) for Great Britain (England, Scotland and Wales). This model has been run with the rainfall and potential evaporation for the Future Flows Climate datasets (11 ensembles of the HadCM3 Regional Climate Model or RCM). The following results have been produced: • For groundwater bodies in England and Wales: o The mean, standard deviation and the following percentiles: 10, 25, 50, 75, 90 (absolute values of annual recharge produced by ranking annual recharge values) have been produced for annual recharge totals for the following periods: simulated historic (1950-2009), 2020s (2010 - 2039), 2050s (2040 - 2069) and 2080s (2070 - 2099). o The 25th percentile and 75th percentile for the simulated historic recharge for each month have been calculated. The estimated daily recharge values were aggregated to monthly values first and the analysis was undertaken using these monthly values. Further, a proportion of recharge values above and below these values for the future climate has been calculated. o Mean monthly recharge values were calculated for each month for the simulated historic period. The change in recharge value for each month in absolute terms compared to monthly value calculated for the historic simulation was calculated for the 2020s (2010 - 2039), 2050s (2040 - 2069) and 2080s (2070 - 2099). o Monthly change factors (percentage difference between monthly average recharge for future climate and historic simulation) for each groundwater body for each of the 11 ensembles were produced. These have been summarised in maps of England and Wales, which illustrate for each month the minimum, maximum and median monthly change factor from all the ensembles for each groundwater body. • River Basin Management Districts (RBMD) in England and Wales: o The mean monthly recharge value was calculated for each month for the RBMD. The change in recharge value in absolute terms was calculated for the 2020s (2010 - 2039), 2050s (2040 - 2069) and 2080s (2070 - 2099). o The total recharge volume for the RBMD for the time periods 1961-90, 1971-00 and for the 2020s (2010 - 2039), 2050s (2040 - 2069) and 2080s (2070 - 2099) was calculated. o Empirical cumulative distribution functions (ECDF) have been produced for seasonal (spring, summer, autumn and winter) as well as monthly averages for historic simulation (both 1961-1990 and 1971-2000) as well as for the 2020s, 2050s and 2080s. Generally the recharge season is shorter in the future. For the historical simulation (1950-2009) the recharge season is between five to seven months each year (September to April). It appears that this is reduced to three to four months for the future climate predictions. This is seen in both the changes in 25% / 75% recharge values and the monthly differences. There appears to be agreement between ensemble outputs. This could make aquifers more vulnerable to droughts if rainfall fails in one or two months rather than a prolonged dry winter as can occur now. When recharge volumes were produced for the RBMDs then the volumes tend to increase from the historical simulation to the 2020s/2050s, but more significantly in the 2080s. For example in the Thames RBMD the average recharge volume increases from 67 x 106 Ml/d in the 2020s/2050s to just over 73 x 106 Ml/d in the 2080s. However, the range of possible outcomes also increases and so one possible future outcome is that recharge volumes could reduce. The recharge season appears to be forecast to become shorter, but with greater amount of recharge “squeezed” into fewer months. This is acceptable for ensuring that recharge for groundwater water resources is maintained from a water balance perspective, but could result in greater “lumpiness” of the recharge signal. This increased “lumpiness” could result in flashier groundwater level response and potentially greater drought vulnerability. Groundwater drought could, therefore, occur if rainfall “fails” for one month, i.e. recharge totals are reliant on fewer months of rainfall. Finally, the results show that the balance between climate variability and climate change shifts towards the end of the future period (2010-2099) with a stronger climate signal being observed in changes to the recharge values in the 2080s than either of the 2020s or 2050s. Given the amount of data produced, a more detailed examination of the results for groundwater bodies would enable more value to be gained from the work. Alongside this, understanding how water balances for the RBMD varies in the future would be beneficial. Three issues should be examined: 1) Disaggregation of recharge volumes for the River Basin Management Districts to examine how recharge to individual aquifers may change; 2) Shortening of recharge season and vulnerability to drought; and 3) Variability of results from the ensembles and likely worse cases. Finally, whilst the initial analysis has focussed on how recharge will change for water resources, no consideration of groundwater flooding has been included and this should be examined

Application of the recharge model code ZOODRM to the British Mainland under conditions of climate change : scoping sources of uncertainty

This report summarises the likely sources of uncertainty associated with the GB recharge model and its application to the 11 ensembles of RCM produced for the Future Flow and Groundwater Level datasets. It identifies the sources of uncertainty in the base model as applied to historical data (1962-2010). The range of responses caused by the application of the 11 ensembles is presented and discussed. Recommendations for further work include quantifying the parametric uncertainty associated with the base model

Malawi Hydrogeological and Water Quality Mapping: Assessing Groundwater Resources Under Extreme Weather

The distributed recharge model developed by Scheidegger et al. (2015) is used to estimate the recharge values under extreme weather events. Synthetic extreme dry and wet rainfall and evaporation time series are produced by repeating a dry or a wet year within the historical rainfall and evaporation time series. The Standardised Precipitation Index (SPI) method is used to identify the most wet and most dry years. Heat maps showing the severity of drought or wet periods across the country are used. These maps show inconsistencies of the calculated indices across the country, with oddities observed in the north part of the country. Six scenarios are considered in which, the wet year is repeated once, twice, and three times and then the dry year is repeated in the same fashion. The estimated long term average recharge values are compared to the historical ones. On average, the groundwater system is expected to be in shortage of 9% of historical long term average recharge values calculated for the country when four successive years of drought years are considered. The groundwater system contains approximately 11 % more resources than that is calculated historically when four successive wet years are considered. AquiMod lumped groundwater model is used to estimate representative transmissivity and storage coefficient values for three catchments. Groundwater levels recorded at the boreholes in Chitipa, Endongolweni School, and Namwera are used for this purpose. The numerical model produces acceptable groundwater time series for the first two boreholes but fails to produce the groundwater level fluctuations at the Namwera borehole. It is believed that inconsistencies between the calculated recharge and the groundwater level time series are the reason for this failure. The optimised hydrogeological parameters lead to transmissivity values varied between 20 and 1500 m2/day. Storage coefficient (specific yield) on the other hand varied between 0.02 and 0.3. The AquiMod models were run using the synthetic meteorological extreme scenarios and the groundwater level fluctuations are compared to those produced using the historical recharge values. The uncertainties associated with the determination of extreme weather periods in the northern Malawi are propagated in this modelling exercise. Whereas the higher extreme weather signals in the south lead to the determination of clearly identifiable extreme weather events, the less clear signals in the north induce the production of incorrect synthetic wet scenarios for this region

Improved understanding of groundwater flow in complex superficial deposits using three-dimensional geological-framework and groundwater models: an example from Glasgow, Scotland (UK)

Groundwater models are useful in improving knowledge of groundwater flow processes, both for testing existing hypotheses of how specific systems behave and predicting the response to various environmental stresses. The recent advent of highly detailed three-dimensional (3D) geological-framework models provides the most accurate representation of the subsurface. This type of modelling has been used to develop conceptual understanding of groundwater in the complex Quaternary deposits of Glasgow, Scotland (UK). Delineating the 3D geometry of the lithostratigraphical units has allowed the most detailed conceptualisation of the likely groundwater flow regime yet attempted for these superficial deposits. Recharge and groundwater flow models have been developed in order to test this conceptual understanding. Results indicate that the direction of groundwater flow is predominantly convergent through the permeable, relatively thick Quaternary deposits of the Clyde valley towards the River Clyde, which runs through Glasgow, with some indication of down-valley flow. A separate nearby system with thick and potentially permeable Quaternary deposits, the Proto-Kelvin Valley, may also be a significant conveyor of groundwater towards the River Clyde, although the absence of local data makes any conclusions conjectural. To improve the robustness of the current model there is a need for an overall increase in good quality groundwater-level data, particularly outside central Glasgow. A prototype groundwater-monitoring network for part of Glasgow is an encouraging development in this regard. This would allow the development of a time-variant groundwater model which could be used to study future modelling scenarios

Malawi Hydrogeological and Water Quality Mapping: National Scale Recharge Estimation

A toolbox of different recharge values and a distributed recharge model have been applied to estimate the recharge values over Malawi. The toolbox is prepared within Microsoft Excel and coded using Visual Basics. The distributed recharge calculation is undertaken using the BGS ZOODRM model. The model uses gridded daily rainfall and potential evaporation data as well as gridded landuse, topography, soil, and river data to calculate recharge. The distributed recharge model is calibrated by matching the simulated overland flows to the observed ones at selected gauging stations. However, difficulties were encountered during the calibration of the recharge model due to: (i) the resolution of the model grid being relatively coarse so that the topographical characteristics could not be fully captured, (ii) the number of runoff zones specified in the model not being enough to represent the characteristics of the study area, and (iii) there being a need to improve the representation of land cover in the model since the land cover affects the estimated recharge values. The estimated recharge values presented in this study are highly affected by the quality of data used in the distributed recharge model. Comparing the recharge values estimated from the recharge model and averaged over the district areas to the recharge values calculated using the recharge toolbox, it was clear that the former agree with the values of at least one analytical method included in the toolbox. However, there was no consistency of agreement, i.e. the recharge values produced by the distributed model did not agree with one particular method. The sensitivity analysis results indicate that the recharge values are highly affected by the soil type parameter values specified in the model and by the definition of spatial distribution of land cover. To improve the accuracy of recharge calculations using the distributed recharge model, it is recommended that maps with a better representation of these features are included in the model. In addition, further model calibration runs are needed to improve the quality of the estimated recharge values. This can be only achieved by obtaining better field data

Assessing future flood risk at BGS and NERC observatory sites : summary report

UK Research and Innovation (UKRI) recognises the problems posed by climate change, its impact on society, and the need for positive action to address the environmental sustainability challenges we now face. By 2040, UKRI aspires to be ‘net-zero’ for its entire research undertaking, which includes reducing and mitigating all carbon emissions from UKRI owned operations (UKRI, 2020). Surface water flooding can cause disruption to people’s daily activities, businesses, and societal functioning, consequently increasing the pressure on natural resources. UKRI aims to understand the risk of flooding to its properties to act where possible to enhance climate resilience. This Summary Report describes work undertaken by the British Geological Survey (BGS) in partnership with the Natural Environment Research Council (NERC) to investigate the risk of flooding to the BGS Keyworth and BGS Edinburgh sites, and to four NERC observatory sites (at Capel Dewi, Eskdalemuir, Hartland, and Herstmonceux). Flood risk was assessed under both ‘current’ and ‘future’ climate conditions. After reviewing existing assessments of the risk of flooding at these locations, additional flood analyses and modelling were undertaken for the sites that have been mapped as being at risk of fluvial or pluvial flooding. These sites are BGS Keyworth, BGS Edinburgh, and the National Centre for Atmospheric Science (NCAS) Capel Dewi Atmospheric Observatory (CDAO). This report summarises the findings from the analyses and hydraulic modelling studies of the three sites. It is accompanied by a second report, which provides more detailed technical information (Nagheli et al., 2022). Flooding due to direct heavy rainfall (pluvial flooding) or due to overflowing surface water features (fluvial flooding) could cause water to inundate areas of the sites investigated, potentially resulting in business disruption and damage to infrastructure. The risk of this is assessed by evaluating whether a feature would be affected by surface water or not, and if so, how often it would be expected. The UKCEH Flood Estimation Handbook (Institute of Hydrology, 1999) methodology was used to obtain profiles of rainfall over time for design storms (see Glossary). The ReFH2 software (the Revitalised Flood Hydrograph rainfall-runoff method version 2; Kjeldsen, 2006) was used to estimate the corresponding surface runoff hydrographs for catchments above points of interest. The HEC-RAS flood modelling software (US Army Corps of Engineers, 2022) was used to simulate fluvial flooding. The SWMM modelling software (Storm Water Management Model; US EPA. 2022) was used to simulate pluvial flooding and to assess the capacity of drainage infrastructure (for BGS Keyworth only). The assessment of how flood risk will change in the future makes use of climate change ‘uplift’ factors. These factors have been used to shift historical design storms. Uplift factors have been estimated using the latest UK Met Office Hadley Centre climate projections—the UKCP18 projections—by the UKRI-funded FUTUREDRAINAGE project (Chan et al., 2021). Factors are only available for a ‘worst case’ atmospheric greenhouse gas concentration trajectory (referred to as a Representative Concentration Pathway or RCP)—the RCP8.5 pathway. Based on these uplift factors, Table 1 summarises how flood risk at each of the sites is predicted by the modelling to change between the historical period (1961–1990) and the two future time horizons considered: the 2050s (2041–2060) and the 2070s (2061–2080). The following findings and recommendations (see also Appendix 2) are presented for the three sites considered: BGS Keyworth • The site is not at risk of flooding from rainfallrunoff causing the water level within the channels running along the north-west and north-east of the site to rise and inundate parts of the site. • The critical storm duration (see Glossary for definition) for BGS Keyworth was calculated to be seven hours. • There are three culverts in the channel along the north-west of the site. If we adjust the historical 7-hour duration, 100-year return period summer storm to account for climate change, then the modelling indicates that the culverts in the drainage channel along the north-west of the site will surcharge but not result in inundation of any parts of the site. (Summer and winter storms are treated separately statistically by flood hydrologists because summer storms are more intense). • Considering the same storm as described in the previous bullet, then if it is assumed that the bottom half of the culverts become blocked, the modelling predicts that the Platt Lane entrance to the site will be inundated by approximately 20 cm of water. No other part of the site would be affected. • Again, considering a 7-hour storm with a return period of 100 years (calculated using data for the period 1981–2020), analysis of the UKCP18 climate projections for RCP8.5 suggests that the frequency of this event will change to: » 1 in 20 years over the period 2021–2040 » 1 in 10 years over the period 2061–2080 • BGS facilities team should inspect the culverts at least annually and arrange for any debris to be cleared by the appropriate authority, if necessary. • BGS should make Nottinghamshire County Council, the Lead Local Flood Authority (LLFA) for Keyworth, aware of this work, given the potential vulnerability to flooding of the new homes recently built on the northern side of Platt Lane, and of Severn Trent Water’s sewage pumping station at the corner of Platt Lane and Nicker Hill. • There has not been sufficient information about the site’s drainage network to assess the risk of water appearing on the ground surface when the drainage network becomes surcharged. Furthermore, the development of a model to do this would be a complex task. Consequently, we have modelled the capacity of the subsurface drainage pipes and used this as a proxy to indicate which parts of the system are more likely to cause water to pond on the surface. Those pipe sections that have been simulated to surcharge, or exceed 90% of their capacity, during a 30-minute storm, need further investigation. The model simulates that 6% of the network’s pipes exceed 90% of their capacity during a 30-minute, 10-year return period storm, which increases to 9% during a 30-minute, 75-year return period storm. First, the slopes and lengths of the problematic network sections should be measured accurately, and the modelling exercise repeated to confirm the findings of this study. Updating and rerunning of the model would be relatively quick. After confirming the fidelity of the model, several potential solutions could then be reviewed, and their costs and benefits evaluated against the level of risk that NERC BGS are willing to accept. Solutions could include replacing small diameter pipes with larger pipes, increasing the slopes of the pipes, optimising the size of catchment areas generating runoff by altering the direction of surface flow paths/directions. It is important to maintain the drainage infrastructure to avoid surcharging of the network and flooding. BGS Edinburgh • The levee and flood gates constructed along the Murray Burn in 2020 have enhanced the protection of the Lyell Centre. However, our modelling predicts that the Lyell Centre would still be affected by flood water under a 20-year return period storm. We conclude that the levee is not sufficiently high at its downstream end and, based on our new drone-based LIDAR survey of land surface elevations, flood water overtopping the levee here flows towards the Lyell Centre. If it is considered that the degree of flood protection is currently insufficient, we recommend that NERC and Heriot Watt University discuss what the options are for increasing the level of protection to the Lyell Centre. For example, this could include extending the levee downstream and increasing its height, or potentially increasing the crosssectional area of the channel. • The critical storm duration for BGS Edinburgh was calculated to be seven hours. Considering a 7-hour storm with a return period of 100 years (calculated using data for the period 1981-2020), analysis of the UKCP18 climate projections for RCP8.5 suggests that the frequency of this event will change to: » 1 in 20 years over the period 2021–2040 » 1 in 7.1 years over the period 2061–2080 • Our modelling has shown the potential for flooding of other buildings on the Heriot Watt campus, e.g. the Energy Academy and the buildings north-east of the Lyell Centre on the opposite side of the Murray Burn and Research Avenue South. This report should be shared with the Heriot-Watt estate management department to make them aware of the risks to the occupiers of these buildings, and to allow them to consider any necessary actions. NCAS Capel Dewi Atmospheric Observatory (CDAO) • The south-east corner of the site was flooded on 21 January 2018. Measurements of rainfall every 10 minutes during this day have been made available by the CDAO’s Project Scientist. Comparison against long-term historical observations of rainfall has indicated that the design storm that most closely matches the peak rainfall intensity and total rainfall of the observed storm has a 7-hour duration and 30- year return period. • Land surface elevation data for the site are only available on a relatively coarse, 5 m grid. Because of this, there is significant uncertainty about the cross-sectional shape, and slope, of the Afon Peithyll, which flows east to west along the south of the site. The results of the modelling must, therefore, be considered as ‘indicative’. • For a 7-hour, 30-year return period design storm the current model simulates flooding that was more extensive than that observed in January 2018. However, it does indicate the area of the facility that is at higher risk—the south-east and east of the site, which is consistent with the observations. • Simulation of the influence of the culvert (approximately 300 m downstream of the site) and whether it is partially blocked or not, suggests that it has little impact on the flood risk of the site. • The critical storm duration for the site was calculated to be four hours. The modelling suggests that a 4-hour storm with a return period of seven years will initiate out of bank flooding at the south-east corner of the site. • Considering a 4-hour storm with a return period of 100 years (calculated using data for the period 1981–2020), analysis of the UKCP18 climate projections for RCP8.5 suggests that the frequency of this event will change to: » 1 in 20 years over the period 2021–2040 » 1 in 10 years over the period 2061–2080 • A survey of the Afon Peithyll and its floodplain is needed to define the dimensions and slope of the channel accurately and improve confidence in the model. • A number of engineering options are listed that could be considered to protect the site from flooding; their viability would depend on the characteristics of the site, cost, and possible environmental impacts. • Consideration could be given to the feasibility, and costs and benefits of moving infrastructure located in the south-east of the site, where flood risk is higher, to another part of the site