Antenna instrument carried by spacecraft is complementary to dedicated dust detectors by registering transient voltage perturbations caused by impact-generated plasma. The signal waveform contains information about the interaction between the impact-generated plasma cloud and the elements of spacecraft – antenna system. Variability of antenna signals from dust impacts has not yet been systematically characterized. A set of laboratory measurements are performed to characterize signal variations in response to spacecraft parameters (bias voltage and antenna configuration) and impactor parameters (impact speed and composition). These measurements demonstrate that dipole antenna configurations are sensitive to impact location because of how the asymmetric expansion of impact plasma cloud produces different signals among antennas. This result revises previous conclusions that dipole antenna configurations should be insensitive to impacts. When dust impacts occur at low speeds, antenna instruments typically register smaller amplitudes and less characteristic impact signal shapes. In this case, impact event identification becomes challenged by low signal-to-noise ratios and complex waveforms, indicating the compound nature of non-fully developed impact-generated plasmas. Laboratory studies of aluminum dust particle hypervelocity impacts were used to explore the dependence of impact waveform variability on dust composition. No significant variations were determined compared to common iron dust measurements, consistent with prior studies. Additionally, electrostatic model fitting is used to obtain impact plasma parameters from antenna-detected waveform signals. The recovered parameters are comparable to those from Fe dust. This suggests a similarity of fully developed impact plasma cloud behaviors upon hypervelocity impact.

Shear-wave splitting measurements are commonly used to resolve seismic anisotropy in both the upper and lowermost mantle. Typically, such techniques are applied to SmKS phases that have reflected (m-1) times off the underside of the core-mantle boundary before being recorded. Practical constraints for shear-wave splitting studies include the limited number of suitable phases as well as the large fraction of available data discarded because of poor signal-to-noise ratios (SNRs) or large measurement uncertainties. Array techniques such as beamforming are commonly used in observational seismology to enhance SNRs, but have not been applied before to improve SmKS signal strength and coherency for shear wave splitting studies. Here, we investigate how a beamforming methodology, based on slowness and backazimuth vespagrams to determine the most coherent incoming wave direction, can improve shear-wave splitting measurement confidence intervals. Through the analysis of real and synthetic seismograms, we show that (1) the splitting measurements obtained from the beamformed seismograms (beams) reflect an average of the single-station splitting parameters that contribute to the beam; (2) the beams have (on average) more than twice as large SNRs than the single-station seismograms that contribute to the beam; (3) the increased SNRs allow the reliable measurement of shear wave splitting parameters from beams down to average single-station SNRs of 1.3. Beamforming may thus be helpful to more reliably measure splitting due to upper mantle anisotropy. Moreover, we show that beamforming holds potential to greatly improve detection of lowermost mantle anisotropy by demonstrating differential SKS-SKKS splitting analysis using beamformed USArray data.

Mercury’s surface is dominated by tectonic landforms formed by compression. Other than within basins, extensional landforms are not well known and have been presumed to be much rarer, with only a handful reported [1]. To date, two types of extensional grabens associated with lobate scarps have been described in literature: pristine back-scarp grabens associated with small lobate scarps (10s of kms in length and 10s of metres in relief) [2] and crestal grabens found on Calypso Rupes (381km in length and ~1km in relief) [3], [4]. This study identifies that such extensional grabens found on lobate scarps are much more widespread than previously recognised. These form when thrusting produces a hanging wall anticline, and local tensional stresses along the anticlinal axis cause antithetic faults to form in the folded strata, parallel or sub-parallel along the hinge zone, producing a down-dropped fault block. These small-scale features (often less than 1km in width, 10s of kms in length and likely 10s to 100s of metres in depth) are not expected survive 100s of millions of years because of regolith formation and impact gardening masking their signature [1], [2]. Our discovery and documentation of more extensional grabens may indicate that significant movement on many of Mercury’s large lobate scarps persisted until geologically recent times. [1] P. K. Byrne, C. Klimczak, and A. M. C. Sengör, “The Tectonic Character of Mercury,” in Mercury : The View After MESSENGER, 1st Editio., S. C. Solomon, L. R. Nittler, and B. J. Anderson, Eds. Cambridge: Cambridge University Press, 2018, pp. 249–286. [2] T. R. Watters, K. Daud, M. E. Banks, M. M. Selvans, C. R. Chapman, and C. M. Ernst, “Recent tectonic activity on Mercury revealed by small thrust fault scarps,” Nat. Geosci., vol. 9, no. 10, pp. 743–747, 2016. [3] C. Klimczak, P. K. Byrne, A. M. C. Şengör, and S. C. Solomon, “Principles of structural geology on rocky planets,” Can. J. Earth Sci., vol. 56, no. 12, pp. 1437–1457, Dec. 2019. [4] M. E. Banks et al., “Duration of activity on lobate-scarp thrust faults on Mercury,” J. Geophys. Res. E Planets, vol. 120, no. 11, pp. 1751–1762, 2015.

Polycyclic aromatic hydrocarbons (PAHs), emitted from combustion of biofuels and fossil fuels, are toxic compounds and known to cause lung-cancer. Integrating a global atmospheric chemistry model and plausible future emissions trajectories, we assess how global PAHs and their associated lung cancer risk will likely change in the future. Benzo(a)pyrene (BaP) is used as an indicator of cancer risk from PAH mixtures. From 2008 to 2050, the population-weighted global average BaP concentrations under all RCPs consistently exceeded the WHO-recommended limits, primarily attributed to residential biofuel use. In developing regions of Africa and South Asia, PAH-associated lung-cancer risk increased by 30-64% from 2008 to 2050, due to increasing use of traditional biofuels with population growth. With the stringent air quality policy, PAH lung-cancer risk substantially decreases by ~80% in developed countries. Climate change is likely to have minor effects on PAH lung-cancer risk compared with the impact of emissions.

The principal structural elements of the Himalayan arc can be traced more or less continuously for nearly 2500 km. It is therefore understandable that along-strike variations in structure and denudation have not received the same attention as equivalent arc-normal trends. However, it is now clear that arc segmentation can be controlled by lateral variations in the geometry of the Main Himalayan Thrust (MHT). The Bhutan Himalaya has a distinctive physiography and hosts nominal modern seismicity despite experiencing long-term strain accommodation comparable to the wider arc. This enigmatic section of the orogen presents an opportunity to test the case for local arc segmentation through applied tectonic geomorphology. By integrating low temperature thermochronology, cosmogenic radionuclide methods and quantitative geomorphometry, this study documents the spatial and temporal variability of denudation to infer partitioning of deformation across crustal structures. Laboratory methods include apatite fission track (AFT), and (U-Th)/He dating of zircon from in situ bedrock, synorogenic sediments and modern detrital samples. Additionally, 10Be concentrations from detrital quartz samples adds to a nation-wide compilation of previously published data. Results suggest prominent along- and across-strike variation in deformation within Bhutan. High normalised channel steepness and hillslope characterise a prominent east-west trending zone of elevated millennial-scale erosion rates. Here termed the Naka Zone, this geomorphic region is coincident with the estimated rupture extent of an early 18th Century great earthquake and terminates to the east in the vicinity of the Kuru Chu reentrant in the Main Central Thrust (MCT). Greater Himalaya basement rocks west of the Sakteng Klippe show a phase of rapid, monotonic cooling, the timing of which is largely latitude-dependent, consistent with exhumation above a mid-crustal ramp on the MHT ~100 km from the front followed by horizontal translation above the AFT partial annealing zone. This framework explains the decoupling of AFT ages in sampled catchments from millennial-scale erosion rates. Small catchments that straddle the MCT show bimodal distributions in single grain AFT ages, suggestive of activity on the MCT during the late Miocene. Further, central ages show a marked decrease towards Arunachel Pradesh, suggesting that in far eastern Bhutan the mid-crustal ramp extends towards the foreland, possibly invoking a lateral ramp. Synorogenic detrital thermochronometers are unreset and thus provide information on source area bedrock cooling and provenance. ZHe and AFT age distributions in the Siwaliks are bimodal. Comparisons with large modern drainage systems links a young age peak (Mio-Pliocene) to the Greater Himalaya and a dominant older age peak (Mid Miocene) to the Lesser Himalaya and points to persistent elevated topography in the range front east of Kuru Chu.

Basal slip along glaciers and ice streams can be significantly modified by external time-dependent forcing, although it is not clear why some systems are more sensitive to tidal stresses. We have conducted a series of laboratory experiments to explore the effect of time varying load point velocity on ice-on-rock friction. Varying the load point velocity induces shear stress forcing, making this an analogous simulation of aspects of ice stream tidal modulation. Ambient pressure, double-direct shear experiments were conducted in a cryogenic servo-controlled biaxial deformation apparatus at temperatures between -2°C and -16°C. In addition to a background, median velocity (1 and 10 μm/s), a sinusoidal velocity was applied to the central sliding sample over a range of periods and amplitudes. Normal stress was held constant over each run (0.1, 0.5 or 1 MPa) and the shear stress was measured. Over the range of parameters studied, the full spectrum of slip behavior from creeping to slow-slip to stick-slip was observed, similar to the diversity of sliding styles observed in Antarctic and Greenland ice streams. Under conditions in which the amplitude of oscillation is equal to the median velocity, significant healing occurs as velocity approaches zero, causing a high-amplitude change in friction. The amplitude of the event increases with increasing period (i.e. hold time). At high normal stress, velocity oscillations force an otherwise stable system to behave unstably, with consistently-timed events during every cycle. Rate-state friction parameters determined from velocity steps show that the ice-rock interface is velocity strengthening. A companion paper describes a method of analyzing the oscillatory data directly. Forward modeling of a sinusoidally-driven slider block, using rate-and-state dependent friction formulation and experimentally derived parameters, successfully predicts the experimental output in all but a few cases.

The scale of wildfires and their associated smoke plumes have increased in the last four decades and have exacerbated the health risks for people living within wildfire-prone areas. While satellite imagery enables us to monitor the location, abundance, and severity of smoke, datasets such as NOAA’s Hazard Mapping System (HMS) smoke product are unvalidated and may not reflect ground-level smoke conditions. We propose that airports monitoring the presence of smoke may offer a localized constraint on satellite smoke products. Our research aims to validate NOAA’s HMS product by comparing how well the HMS smoke data agree with NOAA’s Integrated Surface Database (ISD) of local, hourly airport data from 2010 to 2020 across the US. Our spatial and temporal analysis shows that the trend in the number of smoke days is similar between the two datasets. HMS smoke plumes are qualitatively categorized into 3 densities: light, medium, and heavy. Particularly, HMS smoke plumes with “medium or heavy” densities have the strongest correlation of r = 0.60 and a mean absolute error of 0.73. We observe the greatest difference in the airport and HMS-derived mean smoke days across the west and east coast, especially in California’s Central Valley and eastern Washington. However, there is a very weak correlation of r = 0.17 between surface-level mean smoke days and from HMS “heavy, medium, or light” density smoke days. Further, using all HMS smoke densities tend to overestimate the trends in and magnitude of smoke days. Based on these results, NOAA’s HMS product is somewhat consistent with trends observed at airports, but caution should be used in assuming equivalence with surface conditions in research investigating wildfire smoke and its consequences for public health.

Understanding of the spatial distribution of near-surface oceanic chlorophyll a (Chl-a) in relation to eddy activity is important because Chl-a is critical to biological production and carbon absorption, and its distribution is closely related to meso-scale eddies and Rossby waves. Chl-a distributions based on satellite observations from 2001 to 2018 were analyzed in association with eddy activity in mid-latitude regions of the five ocean basins (North/South Pacific, North/South Atlantic, and South Indian oceans) and related to physical eddy scales including the internal Rossby deformation radius (LD) and Rhines scale (LR). In the open ocean, the horizontal scale of Chl-a (D) decreased with increasing eddy kinetic energy (EKE), converging to πLD in the high-eddy-activity region. The ratio of zonal (Dz) to meridional (Dm) scales, RD (= Dz/Dm), converged to 1 with increasing EKE, implying isotropic uniformization with meso-scale eddies. In regions of low EKE (especially the central subtropical and eastern parts of each basin), Dm was larger than LD, with a scale similar to πLR. In these regions, Dz values greater than Dm were found (with scales of 500–1000 km), indicating the effects of planetary phenomena on Chl-a. In such regions the sensitivity of D to EKE tended to be higher than in western boundary regions, indicating the influence of meso-scale eddy activity on the Chl-a distribution, even with low EKE.

This paper paves the way for a direct comparison of the process of megathrust earthquakes with cellular automaton (CA) and for modeling the catastrophic singularity of seismic events as a phase transition phenomenon. It is shown that the entropy production rate (EPR), which is a property of thermodynamically non-equilibrium systems, occasionally decreases sharply in the seismic process of the Great East Japan Earthquake (GEJE) of magnitude 9. The timing of the EPR decrease is found to be clearly different from that of earthquakes of magnitude less than 9, but close to the timing of the earthquake of magnitude 9. The decrease indicates a qualitative change from a time-dependent non-equilibrium system towards a static equilibrium system, which can be a phase transition. In the GEJE process, EPR is calculated from the binarized velocity deviation of ground vibrations found to be equivalent to velocity. The equivalence attributes to that the transformation between them does not change the α-tremor which is the curvature of the Fourier amplitude spectrum of the velocity, and that an arbitrary ground vibration can be defined by α-tremor. The α-tremor is a noise. However, it is associated with microearthquakes whose epicenter is close to the GEJE epicenter, and is an important component of the GEJE process. The binarization equivalence allows the ground vibration to be viewed as CA which consists of binary numbers.

Substorm onset is believed to be a fundamental process for magnetic and plasma energy transport in both magnetosphere and ionosphere.Ballooning instability is one of the key trigger mechanism to examine the substorm onset scenario in the near-Earth plasma sheet. For this subject,the kinetic ballooning instability (KBI) in the near-Earth magnetotail is analyzed using the general type of two-dimensional (2D) kinetic sheet equilibria, the so-called generalized Harris sheet equilibria. The kinetic ballooning mode is unstable in the intermediate range of perpendicular wave number (ky) and the equatorial beta (eq). The growth rate of the ballooning mode reduces signicantly with the increase in electron and ion temperatures ratio (Te=Ti) and wave number ky. The kinetic ballooning mode is found to be most unstable in the thin current sheet region at the equatorial location xe ~(9-10)RE, where the ballooning drive term (βeq/LpRc) is dominant on stiffening effect due to the minimum in the normal magnetic field Bz there.Because of the stabilizing effect through the field line stiffening factor and the strong field line stabilization, the ballooning mode is stable close to the Earth and becomes marginally unstable away from the Earth. This suggests the local current sheet thinning may be also an effective trigger mechanism for the onset of ballooning instability in the near-Earth magnetotail.

A large number of studies have confirmed the frequent occurrence of plasma irregularities in the mid-latitude ionospheric trough, but there is little understanding of the distribution characteristics about this feature. Based on Swarm in situ plasma measurements from 2014 to 2020, the diurnal, seasonal, solar activity and geomagnetic activity variations of the occurrence rate of mid-latitude trough region irregularities are analyzed. The results show that for the irregularities with scale size of 7.5-75 km: (1) Both of case and statistical analysis indicate that geomagnetic activity has an obvious inhibitory effect on the formation of irregularities in the mid-latitude trough region, whether on the dayside or nightside. (2) The occurrence rate of mid-latitude trough region irregularities during the day is significantly higher than that at night, and the difference between day and night is significantly greater than the difference between the two walls at the same local time section. (3) On the dayside, the highest and lowest occurrence rate appears in winter and summer, respectively; but on the nightside, the highest and lowest occurrence rate appears in equinoxes and winter, respectively. (4) On the nightside, it shows lower occurrence rate under high solar activity conditions, but no obvious solar activity effect is shown on the dayside occurrence rate.

Urban Heat Island (UHI) is defi ned as increased surface and air temperatures of urban areas ascompared to rural surroundings. Thermal remote sensing data have been used extensively tostudy Surface Urban Heat Island Intensities (SUHII). However, it fails to provide information ondiurnal profi le of UHI as well as information on Canopy Layer Urban Heat Island Intensities(CLUHII). To overcome these limitations, integrated Weather Research and Forecasting (WRF)-Urban model have been employed in this study to downscale meteorological variables to urbanscale (~500 m) for assessment of spatio-temporal and diurnal profi le of SUHII and CLUHII inDelhi Urban Agglomeration (UA). Delhi UA is third largest UA of the world and largest interstate,densely populated and multi nuclei UA of India. WRF model has been set up with two way nesteddomains of 1.5 km and 0.5 km to take into consideration of local as well as regional weatherphenomenon. Simulations has been carried out for a time period of three days (due tocomputationally intensive simulation) in each season viz. 4-6 June, 2017 in summer season and15-17 January, 2017 in winter season. Evaluation of model performance with ground basedobservations revealed improved RMSE values for Temperature at 2m, wind speed and surfacepressure. Analysis of spatio-temporal and diurnal variability of SUHII in the study region revealedmore UHI during nighttime to morning time (maximum SUHII was observed at 5:30 IST), whereasminimum SUHII value were observed during daytime at 11:30 IST and 14:30 IST in summerseason (Figure 1). As a matter of fact, urban area displayed cool island effect at 11:30 IST.Similar observations were noted while studying the pattern of winter SUHII. Diurnal variability inCLUHII which is computed from model outputs of Temperature at 2m also displayed similarpattern of UHI during winter and summer season as displayed by SUHII. However, in winterCLUHII displayed comparatively more magnitude as compared with winter SUHII. Since, urbanareas displayed lower temperature as compared to its surrounding at 11:30 AM time, the time ofpass of thermal remote sensing satellites (pass time 10:30 AM - 11:30 AM IST) raises concernfor SUHII studies especially in arid and semi-arid regions like Delhi which is surrounded by sand or bare soil that heats up faster than urban built up.

The Great Salt Lake (UT) is a hypersaline terminal lake in the US Great Basin, and the remnant of the late glacial-pluvial Lake Bonneville. During the Holocene, hydroclimate variations have been more subtle in the basin. These variations can be investigated by organic geochemical methods within the sediment core GLAD1-GSL00-1B, cored in 2000 and recently well-dated by radiocarbon for the Holocene section (Bowen et al., 2019) with 11 meters representing 8 ka to present. Sediment samples every 30 cm (~200 years) were extracted and the total lipid extracts were analyzed by HPLC-MS to detect the full suite of microbial membrane lipids, including those responsive to temperature and salinity. Modern samples were also collected to provide local calibration for the archaeol-caldarchaeol ecometric (ACE) salinity proxy, where ACE = archaeol/(archaeol + caldarchaeol). ACE detects the increase in lipids of halophilic archaea, relative to generalists, as salinity increases. From currently analyzed data and calibrations, we find Holocene lake salinity estimates ranged from 239 to 283 psu, suggesting persistent hypersalinity with < 50 psu variability across 8 kyr. For comparison, the modern salinity of the lake ranges from 100 to 160 psu in the southern half, and 240 to 270 psu in the north. From ~7-6 ka, salinity estimates were relatively high at 270 to ~280 psu. Following 6 ka, salinity decreases and reaches its lowest value of 239 psu at 4.8 ka. Afterwards, salinity increases and varies between ~250 to ~270 psu, remaining at 270 psu in the last 1 kyr. This new salinity record is compared to available shoreline reconstructions and regional climate records. The temperature proxy, MBT’5Me,­ as calibrated by BayMBT, suggests mean annual air temperature estimates ranged from 12°C to 24°C (compared to modern mean temperature of 13°C). This indicates a substantial, variable complication from salinity in this consistently hypersaline lake, as recently reported for the MBT’5Me­ proxy.

Spread-F (SF) is a feature that can be visually observed on ionograms when the ionosonde signals are significantly impacted by plasma irregularities in the ionosphere. Depending on the scale of the plasma irregularities, radio waves of different frequencies are impacted differently when the signals pass through the ionosphere. An automated method for detecting SF in ionograms is presented in this study. Through detecting the existence of SF in ionograms we can help identify instances of plasma irregularities that are potentially affecting the high-frequency radio wave systems. The ionogram images from Jicamarca observatory in Peru, during the years 2008 to 2019, are used in this study. Three machine learning approaches have been carried out: supervised learning using Support Vector Machines, and two neural network-based learning methods: autoencoder and transfer learning. Of these three methods, the transfer learning approach, which uses convolutional neural network architectures demonstrates the best performance. The best existing architecture that is suitable for this problem appears to be the ResNet50. On a test set of 2050 ionograms the ResNet50 model provides an accuracy of 89 percent, recall of 87 percent, precision of 95 percent as well as Area Under the Curve (AUC) of 96 percent. In addition to the model, this work also provides a labelled dataset of over 28,000 ionograms, which is extremely useful for the community for future machine learning studies.

Wastewater is a valuable resource that requires effective treatment management solutions on a global scale. Wastewater has become a major source of irrigation in peri-urban areas in developing countries. Natural treatment systems (NTS) have recently gained appeal in peri-urban environments due to their lower cost and maintenance requirements. The operating efficiency of natural systems was tested in this study using case studies from Vizianagaram, Andhra Pradesh, India. The efficacy of nutrient (Phosphorous and Nitrogen content) and organic matter removal was investigated in four NTS with varying operation maintenance and loading rates. According to the study, Natural treatment systems have a lot of potential for treating peri-urban wastewater. Waste-stabilization systems outperform systems based on duckweed and hyacinth plants, according to the findings. Regularly maintained and operated systems have an organic and nutrient removal efficiency of over 80%, outperforming others. According to the findings, decentralized, well-maintained Waste Stabilization Ponds (WSP) provide a feasible, self-sustaining, and environmentally beneficial wastewater treatment option for rural irrigation water.

The EU H2020 SafeSpace project aims to develop a prototype pipeline that connects several tools in a modular fashion to address the physics of the Sun – Interplanetary space – Earth’s magnetosphere with the ultimate goal to forecast radiation belts dynamics. We present a part of the pipeline called Helio1D that is dedicated to forecasting the solar wind properties at the Lagrangian L1 point. Helio1D models solar wind propagation using input data obtained from the MULTI-VP model, which itself models solar wind emergence near Sun based on magnetograms and coronal field reconstruction. In particular, we aim to forecast the properties of the regular solar wind, as well as Corotating Interaction Regions and their high-speed streams which are most geo-effective (for radiation belts in particular). We take an ensemble forecasting approach to provide optimum forecast up to 2 – 4 days of lead time. We also couple the Helio1D pipeline with neural network models that predict geomagnetic indices such as the Kp index for magnetospheric space weather forecasting. In this presentation, we will present the Helio1D pipeline status, as well as its benchmarking and calibration in order to provide optimum forecasting in real-time. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870437.

Searching mass-balance analysis is applied to find possible standard oxide composition distributions of Martian blueberries (hematite-rich spherules). This found three groups of complete solution sets to the mass-balance equations consistent with the non-detection of silicates in blueberries (by NASA’s rover Opportunity). Two of these groups were previously unknown. One of the groups has blueberry (standard oxide) distributions nearly identical to one found in 2006, with 99.7 wt% FeO/Fe2O3, 0.3 wt% Ni, and zero content for other oxides. Two of ten investigations found a very small group with composition intermediate to the others. The largest group of 152, 501 complete solution sets have blueberry distributions with average iron oxide content of 91.2 (+/-2.9) wt% and Ni content of 0.30 (+/-0.06) wt%. The main distinguishing feature between the groups is that the blueberry distributions of the largest group have five oxides/elements (MgO, P2O5, Na2O, SO3, and Cl) with a collective, summed weight percentage that averages 6.7 (+/- 2.2) wt%. This result is robust to changes in an SiO2 cut-off that determines inclusion/exclusion in the larger group. Searches over spaces of filtering distributions of basaltic and dusty soils were a methodological advance. The results significantly narrow the possible range of iron oxide weight percentage in blueberries from the conclusions of previous major papers concerned with blueberry composition. The allowed levels of iron oxide are so high, and top, loose blueberries are so plentiful, that blueberries are an attractive source material to start the construction of steel infrastructure for science on Mars.

The traditional metric of streamflow depletion represents the instantaneous change in the volumetric rate of aquifer–stream exchange after a finite period of continuous groundwater extraction. In the present study an alternative metric of streamflow depletion was considered: cumulative stream depletion (CSD), which described the total volumetric reduction in flow from an aquifer to a stream resulting from continuous groundwater extraction over a finite period, at the final time of extraction. A novel analytical solution for the prediction of CSD was derived, based upon a forward solution that accounted for streambed conductance and partial stream penetration. Separately, a novel numerical solution for prediction of CSD was derived, based on the derivation and calculation of an adjoint state solution. The accuracy of these methods was demonstrated through benchmarking against existing analytical solutions and perturbation-based results, respectively. The derivation of the adjoint state solution identified three parameters of relevance to CSD prediction: streambed hydraulic conductivity and thickness, both of which contribute to the lumped parameterization of streambed conductance, as well as aquifer specific yield, which controls the rate at which hydraulic perturbations propagate through an aquifer. The computational advantage of the numerical adjoint solution was highlighted, where a single numerical model can be used to predict CSD resulting from any potential groundwater extraction location. The reduction in computational time required was proportional to the number of potential extraction well locations. If the number of potential locations is large then a reduction in model run time of nearly 100 % can be achieved.