Small Urban River Research Articles

Identification of polar organic chemicals in the aquatic foodweb: Combining high-resolution mass spectrometry and trend analysis

Environmental risk assessment of chemical contaminants requires prioritizing of substances taken up by biota as it is a starting point for potential adverse effects. Although knowledge about the occurrence of known chemical pollutants in aquatic organisms has significantly improved during the last decade, there is still a poor understanding for a broad range of more polar compounds. To tackle this issue, we proposed an approach that identifies bioaccumulative and biomagnifiable polar chemicals using liquid chromatography coupled with electrospray ionization to high resolution tandem mass spectrometry (LC-HRMS/MS) and combine it with trend analysis using hierarchical clustering. As a proof-of-concept, this approach was implemented on various organisms and compartments (sediment, litter leaves, periphytic biofilm, invertebrates and fish) collected from a small urban river. HRMS/MS data measured via data-independent acquisition mode were retrospectively analysed using two analytical strategies: (1) retrospective target and (2) suspect/non-target screening. In the retrospective target analysis, 56 of 361 substances spanning a broad range of contaminant classes were detected (i.e. 26 in fish, 18 in macroinvertebrates, 28 in leaves, 29 in periphyton and 32 in sediments, with only 7 common to all compartments), among which 49 could be quantified using reference standards. The suspect screening approach based on two suspect lists (in-house, Norman SusDat) led to the confirmation of 5 compounds with standards (three xenobiotics at level 1 and two lipids at level 2) and tentative identification of seven industrial or natural chemicals at level 2 and 3 through a mass spectra library match. Overall, this proof-of-concept study provided a more comprehensive picture of the exposure of biota to emerging contaminants (i.e., the internal chemical exposome) and potential bioaccumulation or biomagnification of polar compounds along the trophic chain.

High-frequency monitoring and machine learning models for assessing synoptic variability of suspended sediment flow of a small urban river

High-frequency monitoring and machine learning models for assessing synoptic variability of suspended sediment flow of a small urban river

Extreme hydrological regimes of a small urban river: impact on trace element partitioning, enrichment and fluxes.

The input of trace elements from a small urban river (Las River, Toulon, France) located on the northern Mediterranean coast was studied during both base flow and flood events. A 2-year monitoring period of water flow and suspended particulate matter (SPM) showed a typical Mediterranean hydrological regime: a strong increase in water flow and SPM during short flood periods. During the flood event, an up to 2-fold increase in dissolved trace element (DTM) concentrations and particulate trace element content in SPM (PTM) was observed compared to the baseline discharge. The enrichment factor of elements in the SPM ranges from low or moderate for Co, Ni and Cr (1.0-4.7) to extremely high for Cd (157). However, the enrichment factors decrease from base flow to flood, indicating a dilution effect with a large yield of weathering particles with higher particle size. The most significant total trace element loading occurred during flood, ranging from 78% for As and Ni to 91% for Pb, while PTM loading during flood ranged from 35% for As to 77% for Pb. The specific dissolved fluxes during the flood are significantly higher for Pb, Cu and Zn than in the surrounding rivers, indicating specificity in the catchment (lithology). This study shows the importance of monitoring the transport of pollutants through small urban rivers and their potential impact on the coastal region, especially when they enter small and closed bays, as a receiving pool.

Effect of microbial communities on nitrogen and phosphorus metabolism in rivers with different heavy metal pollution.

Small urban and rural rivers usually face heavy metal pollution as a result of urbanization and industrial and agricultural activities. To elucidate the metabolic capacity of microbial communities on nitrogen and phosphorus cycle in river sediments under different heavy metal pollution backgrounds, this study collected samples in situ from two typical rivers, Tiquan River and Mianyuan River, with different heavy metal pollution levels. The microbial community structure and metabolic capacity of nitrogen and phosphorus cycles of sediment microorganisms were analyzed by high-throughput sequencing. The results showed that the major heavy metals in the sediments of the Tiquan River were Zn, Cu, Pb, and Cd with the contents of 103.80, 30.65, 25.95, and 0.44 mg/kg, respectively, while the major heavy metals in the sediments of the Mianyuan River were Cd and Cu with the contents of 0.60 and 27.81 mg/kg, respectively. The dominant bacteria Steroidobacter, Marmoricola, and Bacillus in the sediments of the Tiquan River had positive correlations with Cu, Zn, and Pb while are negatively correlated with Cd. Cd had a positive correlation with Rubrivivax, and Cu had a positive correlation with Gaiella in the sediments of the Mianyuan River. The dominant bacteria in the sediments of the Tiquan River showed strong phosphorus metabolic ability, and the dominant bacteria in the sediments of the Mianyuan River showed strong nitrogen metabolic ability, corresponding to the lower total phosphorus content in the Tiquan River and the higher total nitrogen content in the Mianyuan River. The results of this study showed that resistant bacteria became dominant bacteria due to the stress of heavy metals, and these bacteria showed strong nitrogen and phosphorus metabolic ability. It can provide theoretical support for the pollution prevention and control of small urban and rural rivers and have positive significance for maintaining the healthy development of rivers.

Ecological state of the small Plyushchikha river within the boundaries of the city of Novosibirsk

The Plushykha River is one of the nine small urban rivers of Novosibirsk feeding the Ob. In its coastal zone there are garden societies, highways, railways, which have a significant impact on its condition. The purpose of this work was to assess the state of the coastal zone and some hydrochemical and physical indicators of the water of the Plyushchikha River within the city of Novosibirsk. According to the results of the observations, erosion of coastal slopes by thawed and stormwater was noted, siltation of the Ivy riverbed is observed in the summer. When studying the physical parameters of water, an increase in the intensity of odor in the spring, summer and winter period was noted to 3.0; 4.8 and 2.8 points, respectively. The color index in winter and spring is 44°, which is 2 times higher than the MPC, in summer — 54°, which is 2.7 times higher than the MPC. There was also an excess of the permissible turbidity value in the spring period by 2.6 times, and in the summer and winter periods by 3.6 times. The pH of the water in summer and winter is slightly alkaline, and in spring it is alkaline (9.0 units), the hardness of the water of the Plushykha River varies depending on the season. In spring, this indicator was 4.62°F, in summer — 5.32°F, and in winter — 10.56°F, which is slightly higher than the MPC (10.0°F). The total alkalinity of the water was 9.5 mg*eq/l in spring, 7.5 mg*eq/l in summer, and 12.54 mg*eq/l in winter, with a norm of up to 7.9 mg*eq/l. The concentration of nitrates in the spring and summer periods exceeded the maximum permissible value for natural reservoirs (0.2–1 mg/l) and amounted to 10.0 and 12.3 mg/l, respectively. The level of nitrite ions in river water in spring and summer was 0.7; 0.4 mg/l at MPC — 0.2 mg/l.

Small Urban River Runoff Response to 2020 and 2021 Extreme Rainfalls on the Territory of Moscow

Small Urban River Runoff Response to 2020 and 2021 Extreme Rainfalls on the Territory of Moscow

The heterogeneity of the hydromorphological responses of a stream to the urbanization of its basin

AbstractMorphological adjustment mechanisms and controls of small urban rivers are rarely studied especially in France. We propose an original hydrogeomorphological approach based on a detailed study of a whole catchment using field data acquired systematically all along the river: (i) channel cross‐sections; (ii) riffle‐pool sequences and (iii) obstacles to flow and rainwater drainage pipes. The entire length of the river was surveyed and the channel geometry (depth and width at bankfull) was measured on a cross‐section every 180 m or at each riffle (depending on which of the two intervals happened to be the shortest). The 357 transects thus established constitute as many elementary units of measurement (EUM) of the hydrographic network. Nine hydromorphological variables were used as a basis to classify the profiles (principal component analysis/hierarchical clustering analysis). The types were compared with 12 anthropogenic constraining variables to explain longitudinal morphological variability and to link morphology to pressures on this scale. The results showed an average incision of 0.50 m (locally over 1 m), an average widening of nearly 1 m (locally over 3 m), and heterogeneous distribution of the riffle‐pool sequences (although not complete disappearance). Systematic analysis of within‐channel forms revealed high morphological diversity, the absence of a linear relationship between the rate of urbanization and incision/erosion, and the absence of longitudinal changes in response to urbanization. The constraints identified are commonly observed in urbanized basins, but the variety of responses to the constraints makes it difficult to understand the system as a whole and prevents uniform ecological restoration along the entire river.

A multimethodological evaluation of arsenic in the Zenne River, Belgium: Sources, distribution, geochemistry, and bioavailability

The distribution and geochemistry of arsenic (As) in water and sediments of the Zenne River, a small urban river flowing through Brussels (Belgium), were assessed based on the results of 18 sampling campaigns performed between 2010 and 2021. In general, concentrations of As sharply increase between Vilvoorde and Eppegem and are up to 6–8 times higher in the section downstream of Eppegem in comparison to the upstream part of the Zenne. The monitoring surveys in which the grab water samples were taken at a 1-hour sampling frequency revealed that the large temporal variability in As concentrations found in the downstream part of the river is driven by the tidal cycle. The diffusive gradients in thin films (DGT) technique was used to assess the DGT labile As species in surface water and sediment porewater. Three DGT sorbents (Metsorb, Lewatit FO 36, and ZrO2) for the determination of total As were applied to compare their performance, and the 3-mercaptopropyl-functionalized silica (3-MFS) was used for the speciation of As(III) in porewater. Arsenic species are fully labile in surface waters as the DGT time-integrated concentrations of As were in good agreement with the average concentrations calculated from the grab samplings. In sediment porewaters, As is predominantly present as non-DGT labile species (66–93 %), and the DGT labile As fraction is dominated by As(III). Flux calculations evaluating the relative importance of different As sources to the Zenne River revealed the presence of a point source on the tributary Tangebeek, which contributes to 87 % of the As load carried by the Zenne River.

Nutrients retention of a series of small dam-impacted urban rivers in northern China

How a series of small rubber dams distributed within urban watersheds impact nutrients transport remains less investigated. To fill this research gap, this study assesses the composition of nitrogen (N) and phosphorus (P) and their retention in five urban river segments across the Qingshui-Yanghe rivers, China from March 2019 to September 2021. The upstream and downstream of the Qingshui river (QR-up and QR-city) were enriched with dissolved N and particulate P, suggesting a greater P contribution of agricultural origin. NH4-N concentrations were lower upstream but increased downstream of the Yanghe river due to the direct discharge of sewage and other human activities. N and P concentrations varied along the urban river and were relatively low at QR-city. A total of 159.2 and 8.4 metric tons/yr, corresponding to 63% and 70% of the TN and TP loading, were trapped within QR-up and QR-city, of which the dissolved N and particulate P load retention accounted for 58% and 78%. N and P retention rates within the river segments sharply decreased from 97 to –320% and were mainly sequestered in the upstream river segments (QR-up- QR-city). The retention rate of nitrate (78%) and dissolved reactive P (67%) were higher than that of TPN (9.75%) and TPP (78%) because of biological assimilation. Further, with retention rates of −320%, the upstream river segments were a net source of dissolved organic P. These results confirm that the small dams have an important nutrient retention function that is highly variable on a spatiotemporal scale similarly to large-scale reservoirs. Due to the cumulative influence of sewage discharge downstream of the Yanghe River, the nutrient load retention is significantly higher than that in the Qingshui river segments. The variations in hydrological regimes due to seasonal events and small dam regulation have a substantial impact on nutrient retention, resulting in higher loads retention in the flood period than in other periods. Overall, the results suggest that management plans must not only focus on decreasing nutrient export from the mountainous area of the Qingshui river basin but also on sewage outfalls and enhancing the hydrodynamic status of the dammed rivers with respect to eutrophication.

Riverine litter in a small urban river in Marseille, France: Plastic load and management challenges

Small urban rivers are thought to be major sources of riverine litter, especially macroplastics, into the ocean. In well-developed countries, waste management infrastructures and recovery systems are sometimes implemented to prevent their emission into the sea meeting environmental and economic goals. The Huveaune River in Marseille, South of France, is a typical case study showing a non-negligible and uncontrolled leakage of riverine litter remains, despite all recovery systems implemented. Giant bar screens are settled over the river to collect riverine litter from the whole water column before water is released into the Sea. In this paper, screened material was characterized during a dry, wet and heavy rainfall period and annual macroplastic mass flows were estimated. The plastic fraction represented 83% by count of the 3147 items sorted and counted. Mass flow of plastic debris ranged between 1.1 and 5.8 mt/yr (equivalent to 2.1–11.4 g/cap/yr), in which 0.4–2.1 mt/yr (equivalent to 0.8–4.1 g/cap/yr) are bypassed to the sea during heavy rainfall periods. Giant bar screens across the Huveaune River prevent 65% of the mass flow to reach the sea annually, but 35% remain uncontrolled. When compared to the Seine River and other European Rivers, macroplastic leakage into the ocean per capita may range between 1 and 10 g/cap/yr. This suggests that end-of-pipe solutions are not enough and further supports urgent regulations of the plastic production on local to global scales to tackle the plastic pollution at its source.

Calculation method of submerged plant biomass in small and medium urban rivers: Based on the investigation and analysis of Shanghai City

沉水植物的盖度和生物量是衡量浅水系统恢复程度的重要指标，但城市河道沉水植物的生境由于人为干扰及修复过程，具有较高的异质性，使得城市河道沉水植物盖度和生物量测定更加困难，目前尚无准确、快速的计算方法.本研究以上海市内中小河道为研究对象，通过实测4条河道330余个代表样方的沉水植物生物，研究了基于采样次数的沉水植物单位面积生物量计算方法、采样布点方法和河道总盖度测算方法.结果显示：（1）至少需30~35次面积为0.04 m²的采样可准确估算上海中小河道内沉水植物单位面积的生物量；（2）样点设置可选用随机或等距设置；（3）利用Rededge-M多光谱相机对河道拍摄5波段影像，并进行5~8次重复处理，可较为准确获得整条河道沉水植物盖度.本研究可为城市中小河道沉水植被恢复、河道的分类管理与保护提供参考及依据.;The coverage and biomass of submerged plants are the key indicators of the restoration level of shallow water systems. But the habitat of submerged plants in urban rivers usually has high heterogeneity because of the human disturbance and restoration process. This makes it more difficult to determine the coverage and biomass of submerged plants in urban rivers and lacks an accurate and fast method. In this study, we measured the biomasses of submerged plants in more than 330 representative plots in 4 rivers to investigate the method of calculating the biomass per unit area of submerged plants using the numbers of samplings, as well as the methods of sampling and calculation of total coverage of submerged plants in rivers. The results showed that:(1) At least 30 to 35 samplings (0.04 m²) are required to accurately estimate the biomass per unit area of submerged plants in small and medium rivers in Shanghai; (2) Random or equidistant setting can be selected for sample setting; (3) Getting the band-5 images of the river channels using the Rededge-M multi-spectral camera image and repeating the process for 5 to 8 times, the coverage of submerged plants in the rivers can be obtained with higher accuracy. This study provides crucial reference and knowledge for the restoration of submerged vegetation in small and medium urban rivers and the management and protection of rivers.

Occurrence and distribution of organic ultraviolet absorbents in sediments from small urban rivers, Tianjin, China: Implications for risk management

Organic ultraviolet absorbents (OUVAs) in the environment have been of increasing concern because of their potential hazards. However, the OUVAs in waters is far from being well studied and little is known about their occurrence in small urban rivers. This study investigated the concentrations and distribution of eleven OUVAs in the sediments from five small urban rivers of Tianjin, China, and found total concentrations in the range of 11.6–189 ng/g dry weight. Relative to other rivers and lakes, no high concentrations of sediment OUVAs were observed in the small rivers. Benzophenone, homosalate and octocrylene were the dominant OUVAs, representing medians of 13.3%, 12.4% and 12.3% of the total concentrations, respectively. Our observed composition profiles of these chemicals were different from those found in most of other waters. The sediment OUVAs may originate more from industrial activities than the use of cosmetics and personal care products in this area. The risk to aquatic organisms from exposure to the sediment OUVAs in these small urban rivers was considered low, except for benzophenone. However, more researches are needed to investigate the pollution and associated risks of these chemicals in urban rivers due to the complexity of their toxicity to aquatic organisms.

Hydrological regime of the urban Setun River

According to the results of 2019-2020 studies, we considered the features of hydrological, thermal, ice regime and water turbidity of the small urban Setun River, one of the largest right tributaries of the Moscow River, flowing in the western part of the city of Moscow. The specific discharge from the Setun watershed is 1.5-2 times and the turbidity is 3 times higher than in natural conditions in the upper Moscow River basin. Due to thermal pollution by wastewater, ice cover forms only in the upper reaches of the river during sustained frosts, and water temperature within the city is 1.5-2.5 degrees higher (up to 6 degrees in winter).

Environmental Antimicrobial Resistance in a Small Urban Mediterranean River: A Focus on Endemic Beta-Lactamases in Clinically Relevant Bacteria

Aquatic ecosystems subjected to anthropic pressures are likely hotspots for emergence or dissemination of antimicrobial resistant bacteria. The city of Montpellier is located on a Mediterranean climate watershed that undergoes strong demographic pressures. The aim of the study is to explore antimicrobial resistance, particularly those of clinical concern, in urban rivers flowing in this urban area. The method developed herein to explore antimicrobial resistance is based on cultural and molecular approaches completed by hydrological, hydrogeological, climatic, and physico-chemical data. Hospital vicinity and urbanization density significantly increase cultivable bacterial community, fecal bacteria from human origin, and prevalence of β-lactamases and extended-spectrum β-lactamases encoding-genes without an increase in 16S rDNA gene abundance. A total of 22 multidrug Enterobacterales have been isolated. All Escherichia coli (n = 10) and Klebsiella pneumoniae (n = 6) isolated on a made-house media carried β-lactamases genes, blaCTX-M being the most prevalent (87%), followed by blaTEM (56%) and blaSHV (37%), 56% of these strains carrying two or three of these genes. In urban settings, water quality and infectious risk are generally linked to wastewater treatment plants effluents. This study shows that running waters in urbanized area contribute to the dissemination of antimicrobial resistance, making these environments a reservoir for resistant bacteria with important consideration.

Urban inputs of fecal bacteria to the coastal zone of Libreville, Gabon, Central Western Africa

Libreville, the largest city in Gabon, adversely impacts the Komo Estuary and the Akanda National Park aquatic ecosystems through discharge of domestic and industrial waste. Fecal Indicator Bacteria (FIB: Escherichia coli and fecal streptococci) were enumerated using culture-based methods in water from 40 sites between 2017 and 2019 including coastal outlets, mangrove channels, open bays and littoral rivers. Contamination levels were high in discharge waters from small urban rivers in Libreville agglomeration, frequently exceeding international safety guidelines, whereas FIB concentrations decreased downstream from the city in main mangrove channels. Littoral forest rivers were significantly impacted by fecal contamination despite the absence of settlements in the watersheds. Protected areas are not effective in avoiding FIB contamination, indicating inefficient waste management. Dedicated management policies should be implemented to reduce both the sanitary concern and global pollution, poorly assessed in a context of demographic increase in tropical littoral zones.

Distribution of platinum (Pt), palladium (Pd), and rhodium (Rh) in urban tributaries of the Scheldt River assessed by diffusive gradients in thin films technique (DGT)

The performance of the newly developed DGT technique for the platinum group elements (PGEs) rhodium (Rh), platinum (Pt) and palladium (Pd) was evaluated in two tributaries of the Scheldt River, the Marque River close to the city of Lille (France), and the Zenne River which flows through the city of Brussels (Belgium). In the Marque River, an interlaboratory comparison was performed between the two laboratories where the DGT techniques dedicated to PGEs were developed (AMGC, VUB & LASIRE, U-Lille). PGEs were also analysed in an effluent of a Brussels hospital and monthly grab sampling was performed at the wastewater treatments plants (WWTPs) of Brussels. The concentrations of the 3 elements are higher in the Zenne River than in the Marque River and much higher Pt concentrations are found in the hospital effluent. Good agreement for Pt was observed between the three selected chelating resins and a relatively good agreement was observed between the two laboratories using the same chelating resin, whereas lower results were observed with the anion-exchange resin. Larger discrepancies between the two laboratories were observed for Pd and no comparison could be made for Rh due to the low natural concentrations. The results show that in small urban rivers with high impact of urbanization, WWTPs are an important source of Pt, resulting from the use of anticancer drugs in hospitals and households. The limited retention of PGEs in WWTPs results in increased concentrations in urban rivers downstream.For Pd and Rh, similar trends were found with other traffic related elements such as Cu, Zn and Pb, showing the highest concentrations in waters collecting runoff from a highway. The data show that these elements, together with Gd, can be useful to trace specific pollution sources and their dispersion.

Use of environmental management data for mass flow estimations of plastic debris in rivers: The Seine River and The Huveaune River, France.

Methods to quantify plastic transport in rivers have greatly improved during the past few years. As a first approach, visual counting is currently the simplest way to assess plastic transport with minimal effort and cost. It usually results in underestimations of plastic input into the sea of about one to two order of magnitude when compared to models such as the Jambeck's approach. The latter shows statistical weaknesses and data availability issues leading to large uncertainties, while visual counting miss the water column compartment and often has a low spatiotemporal representativeness. In order to give another ground-truth estimation of plastic transport able to challenge both models and visual counting, we developed innovative methods based on environmental management data in the Seine estuary (500 m3/s) and the Huveaune River ( 2 m3/s; Marseille, France). First, we used data from institutional cleaning in the Seine estuary that consist in litter collection on riverbanks. Their efficiency was measured based on capture-recapture design. Mass flows of plastic debris were then calculated based on the capture rate over one year, the estimation of the fraction of plastic debris which are never collected (hidden or too small) and the assumption that all plastic debris strand on riverbanks. Second, we used data from bar screens spaced of 3 cm in the Huveaune, a small urban river flowing in Marseille, South France. All the water column is screened, and captured waste are automatically collected in dumpsters. Grab sampling were performed after a dry, a wet and a flood period. The corresponding annual mass flows of plastic debris was then calculated relative to the mean fraction of time corresponding to those hydrological periods over 2017 and 2018. Annual mass flows of plastic debris were normalized to the population in both basins. Although methods were different, mass flows of plastic debris per capita are very similar with 8.5 - 13.6 g/cap/yr for the Seine River and 2.4 - 14.9 g/cap/yr for the Huveaune River. This is one to two order of magnitude lower than the Jambeck's approach. However, when focusing on the fraction ending into the Sea, bar screens in Marseille enable to decrease the mass flow of plastic debris of about one additional order of magnitude, while cleaning of riverbanks decreases it of about 10%. This is related to the nature of the rivers that calls for different solutions, screening the whole Seine River being a tricky idea. Nevertheless, when normalized to water volume, the Huveaune River is visually much more polluted (16.4-102.2mg/m3) than the Seine estuary (9.0-14.5 mg/m3). In onclusion, environmental management data can help to estimate mass flows of plastic debris and calls for better consideration. However, they often need an improved scientific framework.

Effect of Extreme Weather Events on Contaminant Transport From Urban Run-Off to a Fjord System

Urbanization has resulted in increased contaminant run-off in densely populated areas. Climate change is expected to result in a higher frequency of extreme weather events including torrential rainfall and storms. The contaminant levels of polycyclic aromatic hydrocarbons (PAH), chlorinated paraffins (CPF) and selected metals, in a small urban river were monitored during snow-melting and rainfall events to quantify the contribution to the contamination load of receiving waters of the inner Oslo fjord, Norway. Suspended particulate matter (SPM) was characterized with respect to levels of contaminants as well as toxic response using a battery of bioassays. The contaminant flux from the river to the fjord was quantified and assessed relative to sediment data. Historic data for near-shore sediment samples from the fjord were used to document urban input. The results show a clear episodic response in contaminant load emitted from the river to the fjord. The main historic input to the fjord was found to be PAH from pyrogenic sources like coal and wood burning as well as traffic. A significant reduction in the level of PAH was observed since the 1980s. The measured flux of CPF is consistent with on-going societal use despite a ban on the use of short chain CPF imposed in Norway from 2002.

Effects of the underground discharge channel/reservoir for small urban rivers in the Tokyo area

In the midst of global climate change, a large typhoon has hit Japan and unprecedented heavy rainfall is occurring. In large cities in Japan, underground discharge channels and underground regulating reservoirs are being developed to improve the flood control safety.In this paper, we confirm the flood reduction effect of these underground facilities against the rainfall generated by Typhoon Hagibis in the Tokyo area in 2019.In addition, the advantages of underground regulating reservoirs in the metropolitan area are discussed from two aspects: cost and land acquisition. It is confirmed that the underground reservoir type has remarkable advantages in both aspects.

Трансформация водосборных бассейнов центра Москвы под влиянием градостроительства

The center of Moscow has a lengthy and complex evolution. One of its characteristics is a dense network of underground communications of different ages (including manifolds of small rivers). Comparison between the “Leveling plan of the Moscow city” (1888) and the topographic map of Moscow (1984) doesn’t show significant changes of the city center’s relief whose absolute level’s rise hasn’t exceed 0.6 m at an average. Studying small underground rivers, such as Neglinnaya, Presnya, Chichera and Zolotoy Rozhok reveals that since the late 19th century till present time, anthropogenic changes have reduced the density of the drainage network nearly to zero and enlarged the subhorizontal surfaces. Geomorphologic processes have ceased in small urban river valleys on the surface, but suffusion-subsidence phenomena, flooding and deformation of buildings and structures intensify around rivers hidden in collectors, which causes significant damage to the urban economy. The structure and morphometry of watersheds has been simplified, and a significant part of their area has become impermeable. Therefore, despite the reduction in the slope of the terrain, flow velocity, power of the streams, and their erosive potential increased. A threat of rainfall floods still remains.