Surface Runoff Research Articles

The Impact of Storm Sewer Network Simplification and Rainfall Runoff Methods on Urban Flood Analysis

Due to the impact of climate change, the importance of urban flood analysis is increasing. One of the biggest challenges in urban flood simulations is the complexity of storm sewer networks, which significantly affects both computational time and accuracy. This study aimed to analyze and evaluate the impact of sewer network simplification on the accuracy and computational performance of urban flood prediction by comparing different rainfall runoff methods. Using the hyper-connected solution for urban flood (HC-SURF) model, two rainfall runoff methods, the SWMM Runoff method and the Surface Runoff method, were compared. The sewer network simplification was applied based on manhole catchment areas ranging from 10 m2 to 10,000 m2. The analysis showed that the computation time could be reduced by up to 54.5% through simplification, though some accuracy loss may occur depending on the chosen runoff method. Overall, both methods produced excellent results in terms of mass balance, but the SWMM Runoff method minimized the reduction in analytical performance due to simplification. This study provides important insights into balancing computational efficiency and model accuracy in urban flood analysis.

A multi-scale integrative approach to study the impact of a common pesticide, the dimethoate, on a mangrove fiddler crab Tubuca urvillei.

At land-sea interface, mangroves are likely to be exposed to pesticides due to agricultural run-offs. In Mayotte Island (Comoros archipelago, Mozambique Channel), dimethoate (DMT) is found in high concentrations in tomatoes, but no data confirm its presence in mangroves. We aimed at screening the presence of DMT in three mangroves of Mayotte at different levels (highest point above crops, village, upstream mangrove, downstream mangrove) and assessing the impact of DMT coupled with reduced salinity on mangrove crab physiology. To do so, we performed 24-h exposures at sublethal concentrations (10 and 100µg L-1) corresponding to 100 × and 1000 × the environmental standard (no data exist on environmental concentrations), in seawater (SW) and diluted SW (dSW). We exposed male fiddler crab Tubuca urvillei, one of the most common fiddler crabs living in mangrove areas regularly flooded and exposed to agricultural run-offs. Different physiological endpoints were considered: behaviour, acetylcholinesterase (AChE) activity, muscle energy metabolism, DNA oxidative damage and osmoregulatory capacity using hemolymph samples, posterior gills and claw muscle. We confirmed the presence of DMT in one mangrove and the effect of pesticide exposure at the different endpoints. Changes in behavioural and physiological parameters highlighted in this study could warn us of recent pesticide use upstream and help us understand past or future community-level changes in mangrove ecosystems affected by pesticide inputs.

Effect of gypsum on transport of IMX-104 constituents in overland flow under simulated rainfall.

Residue of energetic formulations, which is deposited on military training grounds following incomplete detonation, poses biotic hazards. This residue can be transported off-site, adsorb to soil clays and organic matter, transform or degrade, or taken up by plants and animals. Its harmful effects can be mitigated by localizing the energetics at the site of initial deposition using soil amendments and allowing them to bio- and photodegrade in situ. Small plots with coarse loamy soil were used to study the effect of gypsum (CaSO4·2H2O) on transport and redistribution under simulated rainfall of various sizes of insensitive munition explosive (IMX)-104 particles, which consist of 3-nitro-1,2,4-triazol-5-one (NTO), 2,4-dinitroanisole (DNAN), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tertranitro-1,3,5,7-tetrazocine (HMX). The addition of gypsum more than doubled infiltration and decreased sediment loss by 16% compared to the control. The post-rainfall mass balance of IMX-104 in the order from greater to smaller pools was as follows: (1) soil surface retention, (2) off-site loss to overland flow, and (3) sub-surface infiltration. Overall, the application of gypsum significantly decreased concentration and the total mass loss of dissolved DNAN, RDX, and HMX in surface runoff. In addition, gypsum significantly decreased (for NTO, DNAN, and HMX) or delayed (for NTO, DNAN, RDX, and HMX) the peak discharge of <2mm particulate energetics. The infiltration of NTO in the gypsum treatment was fivefold greater than in the control. Moreover, DNAN and RDX were also present in infiltration, while in the gypsum-free control none were found. Gypsum shifted the total mass balance of energetics toward subsurface flow. This study indicates that gypsum may decrease off-site transport of energetic constituents in the soils that are subject to surface sealing.

Integrated Assessment of Metal Contamination of Soils, Sediments, and Runoff Water in a Dry Riverbed from a Mining Area Under Torrential Rain Events

Dry riverbeds can transport mining waste during torrential rain events, disseminating pollutants from mining areas to natural ecosystems. This study evaluates the impact of these mine wastes on soils, sediments, and runoff/pore water in the La Carrasquilla dry riverbed (southeastern Spain). An integrated approach utilizing geochemical and mineralogical techniques was employed, analyzing water, soil, and sediment samples from both the headwater and mouth of the riverbed. Soil profiles and pore water were collected at 30 cm, 60 cm, and 90 cm deep, alongside sediment and runoff water samples. The assessment of metal(loid) contamination focused on arsenic, cadmium, chromium, copper, iron, nickel, manganese, zinc, and lead, utilizing sequential extraction to evaluate metal partitioning across soil phases. Various pollution indices, including the contamination factor (Cf), pollution load index (PLI), potential ecological risk index (RI), and metal(loid) evaluation index (MEI), were employed to classify contamination levels. The highest level of contamination was reported in the headwater, which suggested anthropogenic activities linked to the presence of mining residues as the major source of metal(loid)s. However, an active deposition of As, Cd, Cu, Fe, Mn, and Zn was reported in the topsoil at the mouth. In the headwater, a quartz and muscovite-rich zone exhibited the highest Cf for Pb (1022), primarily bound to the soil residual fraction (62.8%). At the headwater and mouth, pore water showed higher concentrations of sulfate, Ca, Na, Cl, Mg, and Mn and higher salinity than acceptable limits for drinking water or irrigation established by the World Health Organization. Runoff-water metal concentrations surpassed established guidelines, with MEI values indicating significant contamination by cadmium (36.1) and manganese (19.0). These findings highlight the considerable ecological risk of Pb and underscore the need for targeted remediation strategies to mitigate environmental impacts in the Mar Menor coastal lagoon.

Assessment of the level of heavy metals contamination via sediments quality indices of the Koudiet Medouar Dam and its tributary (Batna, Algeria)

The present study assesses the level of heavy metals concerning sediment from the Koudiet Medouar dam. This dam is intended for the production of drinking water and irrigation. In order to assess the level of contamination of the dam by toxic metals, 216 sediment samples were taken at nine stations upstream and downstream of the dam from 2012 to 2014. At the same time, the physical characteristics of the water and the physicochemical parameters of the sediments were determined. The results, expressed by the mean ± standard deviation, are for water: temperature, 15.5 ± 7 °C; potential of hydrogen, 8.05 ± 0.36; conductivity, 1125 ± 228 μS/cm. For sediments the values are potential of hydrogen, 8.55 ± 0.22; conductivity, 730 ± 347 μS/cm; carbonates, 49.18 ± 18.1%; fraction less than 63 μm 27.06 ± 6.95%; organic matter 3.02 ± 1.2%. Trace metal concentrations followed the order: Mn > Zn > Cr > Cu > Co > Ni > Pb > Cd. The strong correlation among trace metal indicates that these elements have common sources suggesting their association with silted sands. The geo-accumulation index, contamination factors, degree of contamination, and sediment pollution index reveal a polymetallic contamination dominated by two or more elements in which Cd, Cr, and Cu are of greatest concern. The levels of trace metals in the sediments record high concentrations upstream of the dam, especially in the second station of the village, near the dam. Our results reflect the footprint of anthropogenic inputs of cadmium, chromium, and copper resulting from agricultural activities by runoff water and soil erosion as well as domestic water discharges.

New Schiff base covalently bonded Graphene Oxide for removing Chromium(VI) from Surface Runoff.

Hexavalent chromium (Cr(VI)) poses severe health and environmental risk, especially in industrial vicinities where runoff concentrations are elevated by evaporation and sedimentation dynamics. This study investigates the utilization of modified graphene oxide (GO) with abundant active groups as an adsorbent. The novel adsorbent, GO/ATA, was synthesized by covalently attaching a Schiff base (ATA) to GO via a coupling reaction, enhancing its adsorptive properties. The physicochemical properties of GO/ATA were meticulously characterized to ascertain structural and morphological attributes. GO/ATA exhibit exceptional adsorptive capabilities, surpassing the performance parameters of other adsorbents with a maximum of 243.3 mg g-1 at 298 K. The electrostatic attraction between the N-containing functional groups in the graphene oxide and Schiff base composite (GO/ATA) and Cr(VI) is the main mechanism behind the adsorption process; Subsequently, a reduction reaction occurs, facilitated by the thiol and N-containing functional groups in GO/ATA composite, resulting in the transformation of Cr(VI) into Cr(III). This transformation is essential for the following chelation process occurring on the surface of the adsorbent material. Evaluations of recyclability indicated that GO/ATA retains substantial adsorption efficacy, with a reduction from 91.2% to 72.7% over five cycles, thus affirming its recyclability and practical application in the remediation of Cr(VI)-contaminated waterborne environment. Additionally, GO/ATA's effectiveness in removing Cr(VI) from surface runoff was specifically tested, emphasizing its economic and environmental viability.

Effects of low impact development on runoff pollution and water quality resilience in an urbanized estuary area

In urbanized estuary areas, water quality often deteriorates due to the impact of surface runoff or overflow during heavy rainfall events. Low impact development (LID) can mitigate this impact and improve water quality resilience. However, there were few studies on quantifying this effect of LID, particularly in estuary areas. In this study, water quality resilience is expressed as the abnormal rate of water quality during rainfall events and the time required for water quality to recover from abnormality to normal. In this study, a coupled Storm Water Management Model (SWMM) and Environmental Fluid Dynamic Code (EFDC) model is used to examine the effects of LID on runoff pollution and water quality resilience in the Shenzhen River estuary (including Shenzhen River and Deep Bay) in China. The results indicate that (1) The inflow volume into the estuary is not only affected by the drainage area but also by the service area and capacity of the sewer interception system; LID can reduce not only the stormwater runoff but also the overflow from the interception systems along rivers. (2) The marginal benefit of the LID proportion increase in pollution load reduction diminishes as the proportion of LID implementation increases. (3) LID can reduce the high value of pollution concentration caused by rainfall runoff; and the reduction effect on the rivers is greater than that on the bay. (4) The rivers and the estuary have a much higher abnormal rate than the inner bay and the outer bay; however, the estuary and the inner bay have longer recovery time than the rivers and the outer bay. The maximum abnormal rate, average abnormal rate, and recovery time of different indicators in the entire estuary area are decreased by 10%-189%, 6%-71%, and 0.8–1.1 cycles when the runoff from 80% of built-up area is treated by LID facilities; LID can significantly reduce abnormal rate of the rivers and recovery time of the inner bay. Therefore, the proposed metric and model can fully reflect the spatial variations in water quality resilience, and LID can enhance the water quality resilience of the urbanized estuary areas under rainfall.

Validating the Effect of Topography and Geology on Rainfall–Runoff in Mountainous Catchments Using the Improved HYdrologic CYcle Model

ABSTRACTRainfall–runoff characteristics of mountainous catchments are affected by many factors, such as topography and geology. Traditionally, the effects of geology on rainfall–runoff characteristics have been explained using geology, but the differences in runoff characteristics within the same geological settings have not been examined. These differences can be expressed as differences between the hydrological model parameters. However, the effects of geology on the model calculations have not yet been clarified. Thus, this study aims to clarify the effects of topography and geology on model calculations using an improved HYdrologic CYcle (HYCY) model that considers bedrock infiltration. Runoff observations were conducted for approximately 3 years in 19 catchments at 2 sites located in sedimentary rock and granite mountains. Rainfall was recorded at each site. The observed hydrographs were used to optimise the parameters for each catchment using the least‐squares method. The relationship between parameter m and the soil layer storage was calculated using the optimised parameters, representing the percentage of the area contributing to runoff. Furthermore, these results were compared with observational analysis results. The improved HYCY model accurately represented all 19 runoffs. When the total precipitation in 1 event exceeded 200 mm, parameter m became ~1 and ~0.3–0.4 in sedimentary rock and granitic catchments, respectively, which shows the effect of geology. The effects of topography on the parameters were exhibited in Kc and Kb, which calculated the storm flow from the channels and baseflow hydrographs, respectively. However, the parameter distributions exhibited geological differences, namely in parameter Kh, Kb and m. The parameter Kh calculates the overland flow hydrograph. This implies that geological differences affect the probability of the overland flow generation rate and the recession hydrographs of the overland flow and baseflow.

Impact of broiler litter and swine liquid manure on nutrient loss in runoff from three consecutive one acre-inch rainfall events

Manure is an important source of plant nutrients and organic matter that can benefit soil health over time. However, indiscriminate use of manure can lead to environmental problems including eutrophication of water bodies caused by nutrient runoff during precipitation events. There is a need to understand the effect of manure source and application rate on nitrogen (N) and phosphorus (P) forms and their losses during runoff events. In this study, we assessed the impact of application rate of broiler litter (BL) and swine liquid manure (SLM) on runoff volume, soil, N, and P losses using a rainfall simulator and three consecutive 2.45 cm rainfall events. Surface Decatur silty clay loam (0–0.06 m) was collected and packed in trays (0.55 x 0.30 × 0.06 m3). Manure was surface-applied to the soil at equivalent P rates ranging from 62 to 249 kg ha−1 for BL and 5–18 kg ha−1 for SLM, respectively. Rainfall events took place 7, 14, and 21 d after manure application. Results indicated that the runoff volume decreased at the highest manure application rate compared to the lowest manure application rate. The total suspended solids (TSS) loss was lower in control compared to BL and SLM treatments. The loss of nitrate-N (NO3-N) dissolved reactive P (DRP) and dissolved organic P (DOP) in runoff water was maximum at the highest application rates for both the BL and SLM with respect to control. Mehlich 3 extractable P (M3P) and water soluble P (WSP) increased with increasing P application rates for both manure types in soils following post rainfall simulation study. An increase in M3P and WSP, along with a decrease in soil P storage capacity following post-rainfall simulation for higher P application rates, indicates caution should be taken for considering the manure application rate to prevent environmental nutrient loss during runoff events.

Green Infrastructure in Series to Treat Stormwater Runoff from a Highway Overpass

Green Infrastructure in Series to Treat Stormwater Runoff from a Highway Overpass

Structural and dynamic characteristics of horseshoe vortex systems in front of rigid vegetation inclined upstream under conditions of overland flow

Structural and dynamic characteristics of horseshoe vortex systems in front of rigid vegetation inclined upstream under conditions of overland flow

Water and carbon fluxes from a supra-permafrost aquifer to a stream across hydrologic states

Supra-permafrost aquifers within the active layer are present in the Arctic during summer. Permafrost thawing due to Arctic warming can liberate previously frozen particulate organic matter (POM) in soils to leach into groundwater as dissolved organic carbon (DOC). DOC transport from groundwater to surface water is poorly understood because of the unquantified variability in subsurface properties and hydrological environments. These dynamics must be better characterized because DOC transport to surface waters is critical to predict the long-term fate of recently thawed carbon in permafrost environments. Here, we used distributed Darcy’s Law calculations to quantify groundwater and DOC fluxes into Imnavait Creek, Alaska, a representative headwater stream in a continuous permafrost watershed. We developed a statistical ensemble approach to model the parameter variability and range of potential contributions of steady-state groundwater flow to the creek. We quantified the model prediction uncertainty using statistical sampling of in-situ, active-layer soil hydro-stratigraphy (water table, ice table, and soil stratigraphy), high-resolution topography data, and DOC data. Moreover, the predicted groundwater discharge values representing all possible hydrologic conditions towards the end of the thawing season were also considered given the potential variability in saturation. The model predictions were similar to and span most of the observed range of Imnavait Creek streamflow, especially during recession periods, and also during saturation excess overland flow. As the Arctic warms and supra-permafrost aquifers deepen, groundwater flow is expected to increase. This increase is expected to impact stream, river, and lake biogeochemical processes by dissolving and mobilizing more soil constituents in continuous permafrost regions. This study highlights how quantifying the uncertainty of hydro-stratigraphical input parameters helps understand and predict supra-permafrost aquifer dynamics and connectivity to aquatic systems using a simple, but scalable, modeling approach.

Assessment of the Impact of LID Techniques on Water Cycle Recovery in Industrial Complexes

Urbanization and industrialization have significantly disrupted the natural water cycle, leading to increased runoff, flooding, and groundwater depletion. Research on LID (Low Impact Development) techniques is ongoing in order to address these challenges. This study has analyzed the improvement in the water cycle system by applying LID techniques to the Daejeongcheon watershed in Ulsan. Using SWMM, this study has assessed the long-term effects of LID on runoff reduction and water cycle recovery rate improvement. Based on local climate data, topographical information, and regional characteristics, LID elements such as permeable pavements, green roofs, bioretention, and vegetative swales were applied. The results showed that the LID techniques reduced runoff by 8.44% and also improved the water cycle recovery rate by 13.52%. Additionally, the study confirmed that LID techniques effectively contributed to managing runoff from the 25.5 mm rainfall management target. LID techniques are expected to serve as sustainable water management strategies in urbanized and industrialized areas, offering effective restoration and management solutions.

Unveiling Agricultural Soil Runoff: Remote Sensing and Ensemble Deep Learning Models to Evaluate Impact of Climate on Water Quality and Human Health

Unveiling Agricultural Soil Runoff: Remote Sensing and Ensemble Deep Learning Models to Evaluate Impact of Climate on Water Quality and Human Health

Design discharge estimation for small urban districts – an analytical approach

ABSTRACT This paper presents a straightforward design discharge estimation procedure for small urban districts. In this approach, the configuration of the small urban district was simplified into either a rectangular porous overland plane or a V-shaped porous overland model. The Horton equation was used to estimate the infiltration on the overland planes, and the kinematic-wave approximation was applied for runoff simulations. In deriving the runoff equation, the Darcy–Weisbach coefficient was adopted to account for the influences of spatially various flow depths on overland flow resistance. The theoretical derivations were applied to a series of cases and verified by numerical models to demonstrate the applicability of the proposed method. The results showed that the design discharges obtained from the analytical equations are close to those simulated by the numerical model. The analysis procedure developed herein can provide a convenient way for engineers to conduct urban sewer designs.

EROSION IN SOILS ADDED WITH HYDROGEL

Soil erosion is currently the main cause of soil degradation. Therefore, it is urgent to implement technologies that aim to reduce erosion processes. The effects of hydrogel on water storage and its ability to reduce surface runoff and soil losses were evaluated. Experiments were set up in pots and in the field, with different doses of hydrogel and under different managements, respectively. In pots, the treatments were: T0 and T02 - 0 g of hydrogel; T0.5g - 0.5 g; T1g - 1 g; T2g - 2g; T3g - 3 g; T4g - 4g and T5g - 5 g of hydrogel. In the field, 13.3 g of hydrogel/m2 was applied to erosion plots installed in an area with soursop cultivation under different conservation managements, namely: – T1 - Planting in contour lines + stone cordons + grass planting; T2 - Planting downhill, without grass; T3 - Contour planting + grass planting and T4 - Downhill planting + grass planting. The total volume of water percolated in each pot and the surface runoff and soil losses were measured. It was concluded that doses between 4 and 5 g/pot cause increases in water retention of more than 20%, mainly after 4 or 5 wetting and drying cycles. The high variability of the treatments made it difficult to measure the effects of the hydrogel on soil losses, requiring more field studies using the polymer. Keywords: Surface Runoff, Storage, Conservation Practices

Application of Nitrate–Ammonium Nitrogen Fertilization Reduced Nitrogen Loss in Surface Runoff and Infiltration by Improving Root Morphology of Flue-Cured Tobacco

Nitrogen loss in water from farmland has become an environmental issue. Nitrogen fertilizer is the main cause of agricultural non-point source pollution in the Lake Basin, Yunnan. However, it is unclear how different nitrogen fertilizer forms affect water loss from farmland and how the root systems of crops respond. We established five nitrogen fertilizer treatments (100–0% [T1], 75–25% [T2], 50–50% [T3], 25–75% [T4], and 0–100% [(T5)] nitrate–ammonium) and performed an investigation to determine nitrogen loss in water and root morphological parameters of tobacco in Mile County and Chengjiang County. Compared with in the T1, T4, and T5 treatments, the total nitrogen loss in surface runoff was reduced by 4.67%, 11.85% and 9.56% in the T2 treatment and 27.32%, 23.20%, and 31.43% in the T3 treatment, respectively. Similar results were observed for the nitrogen loss due to infiltration. The root biomass was negatively correlated with nitrogen loss. There was greater root biomass, root surface area, and root spatial distribution in T2 and T3 compared with in T1, T4, and T5. These results indicate that 50–50% nitrate–ammonium nitrogen fertilizer can facilitate the root growth of tobacco and reduce nitrogen loss, which provides a reference for agricultural sustainable development.

Best Management Practices to Mitigate Contamination of Karstic Aquifers from Emergency Fire-Control Runoff

We propose best management practices to increase karstic aquifer drinking water supplies’ resilience to potential hazardous material impacts where first responders and public safety officials suspect emergency firefighting runoff has entered the subsurface in the aquifer recharge zone. Karstic aquifers are unique because of their direct openings to the land’s surface, which allows contaminants in runoff or other surface waters to rapidly enter the subsurface and impact aquifer water quality. In the United States, 20% of the land surface is karst, and about a third of the groundwater used for drinking comes from karstic aquifers. Proposed best management practices emphasize on-site, real-time evaluation of the transport and fate of HAZMAT that may enter the subsurface and focus on water quality sampling, runoff and groundwater flow modeling, nontoxic dye tracing, and related studies for use in planning before and during an event and after emergency response has ended. We recommend best management practices for evidence-based screening of high-risk sites to facilitate placement of hazardous material sampling devices and emergency responder deployment. The best management practices, tools, curricula, and training described combine with earlier work by the authors to provide a comprehensive menu of actions to (1) help first responders prevent or limit flushing of hazardous material into a karstic aquifer; (2) help emergency management officials understand the consequences of contamination and issue data-driven geographically focused health and safety risk communications; and (3) help provide health and safety officials with relevant science- and data-based information that can help mitigate human and environmental health risks.

Modeling the effect of land-use change on runoff water quality in the urban watershed: a case study of Settat city, Morocco

ABSTRACT The purpose of this study is to create a model of the quantity and quality of runoff from the urban watershed. The modeling was performed using a personal computer stormwater management model (PCSWMM) tool and was based on washoff and buildup for total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) measured in the field. In addition, low impact development (LID) was used under four different scenarios to improve runoff control of the urban hydrologic cycle and reduce pollutant concentrations. Model performance was analyzed using the R2 and NSE goodness-of-fit indices. Thus, three typical rainfall events, as well as field measurement parameters (TSS, TN, and TP), were used for the model's calibration and validation. The base scenario quantified the runoff volume and pollutant load without any intervention in the runoff process control. Scenarios S2 (BR: bioretention) and S3 (PP: permeable pavement) contributed, separately, in reducing runoff and pollutant load but with relatively small percentages. In addition, the results show that scenario S4 (BR and PP) has the most significant impact on flow reduction, by about 10% compared with the base scenario, as well as on the pollutant load reduction, by about 31, 29, and 40% for the parameters TSS, TN, and TP, respectively.

The cryostratigraphy of thermo-erosion gullies in the Canadian High Arctic demonstrates the resilience of permafrost

Abstract. Thermo-erosion gullies (TEGs) are one of the most common forms of abrupt permafrost degradation. They generally form in ice-wedge polygonal networks where the interconnected troughs can channel runoff water. Although TEGs can form within a single thawing season, it takes them several decades to stabilize completely. While the inception of TEGs has been examined in several studies, the processes of their stabilization remain poorly documented, especially the cryostructures that form following permafrost aggradation in stabilizing TEGs. For this study, we investigated the impacts of two TEGs in the Canadian High Arctic (Bylot Island, NU, Canada) on ground ice content, cryostratigraphic patterns, and geomorphology to examine permafrost recovery following thermal erosion in ice-wedge polygonal tundra. We sampled 17 permafrost cores from two TEGs – one still active (since 1999) and one stabilized (&gt; 100 years old) – to describe the surface conditions, interpret the cryostratigraphic patterns, and characterize the state of permafrost after TEG stabilization. Although the TEG caused discernable cryostratigraphic patterns in permafrost, ground ice content and thaw front depth in the TEGs were comparable to measurements made in undisturbed conditions. We also noted that, once stabilized, TEGs permanently (at the Anthropocene scale) alter landscape morphology and hydrological connectivity. We concluded that, although the formation of a TEG has profound effects in the short and medium term (years to decades) and leaves near-permanent geomorphological and hydrological scars in periglacial landscapes, in the long term (decades to centuries), High Arctic permafrost can recover and return to geocryological conditions similar to those pre-dating the initial disturbance. This suggests that, in stable environmental conditions undergoing natural variability, permafrost can persist longer than the geomorphological landforms in which it forms.