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Mojarrad, Babak Brian
Publications (3 of 3) Show all publications
Wörman, A., Mojarrad, B. B. & Riml, J. (2019). Fragmentation of the Hyporheic Zone Due to Regional Groundwater Circulation. Water resources research, 55(2), 1-21
Open this publication in new window or tab >>Fragmentation of the Hyporheic Zone Due to Regional Groundwater Circulation
2019 (English)In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 55, no 2, p. 1-21Article in journal (Refereed) Published
Abstract [en]

By use of numerical modeling and field observations, this work quantified the effects of catchment-scale upwelling groundwater on the hyporheic (below stream) fluxes over a wide range of spatial scales. A groundwater flow model was developed that specifically accounted for the hydrostatic and dynamic head fluctuations induced by the streambed topography. Although the magnitudes and relative importance of these streambed-induced fluxes were found to be highly sensitive to site-specific hydromorphological properties, we showed that streambed topographic structures exert a predominant control on the magnitude of hyporheic exchange fluxes in a Swedish boreal catchment. The magnitude of the exchange intensity evaluated at the streambed interface was found to be dominated by the streambed-induced hydraulic head across stream order. However, the catchment-scale groundwater flow field substantially affected the distribution of groundwater discharge points and thus decreased the fragmentation of the hyporheic zone, specifically by shifting the cumulative density function toward larger areas of coherent upwelling at the streambed interface. This work highlights the spectrum of spatial scales affecting the surface water-groundwater exchange patterns and resolves the roles of key mechanisms in controlling the fragmentation of the hyporheic zone.

Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2019
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-244783 (URN)10.1029/2018WR024609 (DOI)000461858900020 ()
Note

QC 20190304

Available from: 2019-02-25 Created: 2019-02-25 Last updated: 2019-05-02Bibliographically approved
Lewandowski, J., Mojarrad, B. B. & Wu, L. (2019). Is the Hyporheic Zone Relevant beyond the Scientific Community?. Water, 11(11), Article ID 2230.
Open this publication in new window or tab >>Is the Hyporheic Zone Relevant beyond the Scientific Community?
2019 (English)In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 11, no 11, article id 2230Article in journal (Refereed) Published
Abstract [en]

Rivers are important ecosystems under continuous anthropogenic stresses. The hyporheic zone is a ubiquitous, reactive interface between the main channel and its surrounding sediments along the river network. We elaborate on the main physical, biological, and biogeochemical drivers and processes within the hyporheic zone that have been studied by multiple scientific disciplines for almost half a century. These previous efforts have shown that the hyporheic zone is a modulator for most metabolic stream processes and serves as a refuge and habitat for a diverse range of aquatic organisms. It also exerts a major control on river water quality by increasing the contact time with reactive environments, which in turn results in retention and transformation of nutrients, trace organic compounds, fine suspended particles, and microplastics, among others. The paper showcases the critical importance of hyporheic zones, both from a scientific and an applied perspective, and their role in ecosystem services to answer the question of the manuscript title. It identifies major research gaps in our understanding of hyporheic processes. In conclusion, we highlight the potential of hyporheic restoration to efficiently manage and reactivate ecosystem functions and services in river corridors.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
hyporheic zone, hyporheic exchange flow, surface water-groundwater exchange, ecosystem services, nutrient turnover, refuge, hyporheos, removal of trace organic compounds, emerging pollutants, self-purification capacity
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-266241 (URN)10.3390/w11112230 (DOI)000502264500032 ()2-s2.0-85075554095 (Scopus ID)
Note

QC 20200103

Available from: 2020-01-03 Created: 2020-01-03 Last updated: 2020-01-03Bibliographically approved
Mojarrad, B. B., Betterle, A., Singh, T., Olid, C. & Wörman, A. (2019). The Effect of Stream Discharge on Hyporheic Exchange. Water, 11(7), Article ID 1436.
Open this publication in new window or tab >>The Effect of Stream Discharge on Hyporheic Exchange
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2019 (English)In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 11, no 7, article id 1436Article in journal (Refereed) Published
Abstract [en]

Streambed morphology, streamflow dynamics, and the heterogeneity of streambed sediments critically controls the interaction between surface water and groundwater. The present study investigated the impact of different flow regimes on hyporheic exchange in a boreal stream in northern Sweden using experimental and numerical approaches. Low-, base-, and high-flow discharges were simulated by regulating the streamflow upstream in the study area, and temperature was used as the natural tracer to monitor the impact of the different flow discharges on hyporheic exchange fluxes in stretches of stream featuring gaining and losing conditions. A numerical model was developed using geomorphological and hydrological properties of the stream and was then used to perform a detailed analysis of the subsurface water flow. Additionally, the impact of heterogeneity in sediment permeability on hyporheic exchange fluxes was investigated. Both the experimental and modelling results show that temporally increasing flow resulted in a larger (deeper) extent of the hyporheic zone as well as longer hyporheic flow residence times. However, the result of the numerical analysis is strongly controlled by heterogeneity in sediment permeability. In particular, for homogeneous sediments, the fragmentation of upwelling length substantially varies with streamflow dynamics due to the contribution of deeper fluxes.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
hyporheic zone, transient flow discharge, groundwater-surface water interaction, experimental-modeling study, temperature measurement, depth decaying permeability
National Category
Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:kth:diva-257467 (URN)10.3390/w11071436 (DOI)000480632300121 ()2-s2.0-85073891965 (Scopus ID)
Note

QC 20190830

Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2020-02-04Bibliographically approved
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