<p><p>Clean water is a critical natural resource. We do not have much available: only 2.5% of water on Earth is freshwater and of that only 31% is in liquid form. 96% of the liquid fresh water is groundwater. Unfortunately that resource is subject to contamination by hazardous materials accidentally or illicitly spilled, leaked, or deposited in or on the ground. Among the methods to remediate these disasters, pump-and-treat (P&T) is the most common. The vertical circulation well (VCW) is a P&T configuration with extraction and injection sites within the same well. It can be adapted to many remediation techniques and has been gaining popularity since the 1990s and is often a better alternative to conventional P&T. Conventional P&T and VCWs are typically run with steady flow.</p></p><p><p>The major bottleneck to steady flow remediation is that contaminants become trapped in dead-end pores. In an aquifer there are two types of pores: <it>pass-through</it> pores and <it>dead-end</it> pores. The flow in former completely sweeps through the pore space while the flow does not enter the later; however, the flow through the <it>pass-through</it> pore induces a vortex in the <it>dead-end</it> pore. Under steady flow the only mechanism for contaminants to escape the <it>dead-end</it> pores is molecular diffusion.</p></p><p><p>A similar problem is encountered in the removal of surfactants in the manufacture of semiconductor and the removal of oil residue build-up in small ducts. Manufacturers discovered that pulsed flow would accelerate the mass transfer between the cavities and grooves on these surfaces and the external flow. This was because the unsteady ramp-up in flow rate initiated a deep sweep of the cavities. The unsteady ramp-down in flow rate initiated a vortex ejection where the sequestered vortex is no longer constrained and protrudes from the cavity.</p></p><p><p>We hypothesized that just as pulsed flow improves cleaning of grooved surfaces in several manufacturing procedures, rapidly pulsed pumping (with a period on the order of a second rather than weeks or months) in pump-and-treat groundwater remediation would boost the diffusion-limited removal of contaminants trapped in dead-end pores by generating transient deep sweeps and vortex ejections in these pores. These processes have not yet been exploited in groundwater remediation to any significant degree.</p></p><p><p>We tested our hypothesis in a series of numerical and laboratory experiments. We considered unwashed and washed media. For unwashed media (Chapter 1) we used as a square pore in the numerical domain and crushed glass (for its negligible sorption capacity) in laboratory column studies. For washed media (Chapter 2) we used a smooth dead-end pore constructed with two tangential quarter circles as the pore in the numerical domain and glass spheres in the laboratory column studies. In all our laboratory experiments we used a fluorescent dye, Fluorescein, as a conservative tracer. We used the same parameters in our numerical experiments. However, in some we also considered immiscible contaminants such as NAPLs (Chapter 4).</p></p><p><p>All numerical experiments were conducted with the computational fluid dynamics software, FIDAP. In numerical experiments we studied the contaminant removal from interacting dead-end pores connected to both a straight pass-through pore and a divergent pass-through pore. The latter with the flow somewhat analogous to the radial spreading encountered around a around a well in field applications (Chapter 5).</p></p><p><p>To elucidate the dead-end pore dynamics (Chapter 3), we performed numerical experiments and used a physical model to obtain a relationship between the rapidly pulsed flow frequency and length of the pore. Our dimensional analysis pointed to the change in pressure as the key component in the initiation of transient deep sweeps and vortex ejections, two new pore-cleaning mechanisms.</p></p><p><p>We conclude that the rapidly pulsed flow improves the recovery of contaminants from unwashed, or rough, porous media. In numerical experiments with a pore system consisting of just a single square dead-end pore and a single pass-through pore, at 100 pore volumes pumped the rapidly pulsed flow improved cleanup of the dead-end pore alone by approximately 40%. This translates into a 10% improvement of the cleanup of the pore system (dead-end and pass-through pore). Since the dead-end pore is the bottleneck of the current groundwater remediation, it the first measure that is relevant.</p></p><p><p>In corresponding laboratory column experiments with crushed glass, the dead-end pore volume alone is not known. The cleanup of the whole pore space was improved by roughly 10% with the rapidly pulsed pumping, which corresponds nicely to our numerical results.</p></p><p><p>Our numerical experiments demonstrate that there exists an optimal pulsed pumping frequency that is a function of the local flow velocity and the pore geometry (size and morphology).</p></p><p><p>The contaminant recovery from washed, or rounded, media was not as pronounced in the laboratory experiments and the numerical experiments showed no improvement. While both rapidly pulsed and steady flow recovered all of the contaminant in the laboratory column tests, the difference in the time between the two pumping schemes was approximately 0.9 pore volumes pumped. This improvement is likely to be amplified with sorbing contaminants.</p></p><p><p>Many contaminants are non-aqueous phase liquids (NAPLs), which do not readily dissolve in water. We showed in numerical experiments that rapidly pulsed flow can recover NAPLs with viscosity lower than water, but is not as effective with higher viscosity materials; however, these results were based on a model that did not account for interfacial tension and wetting; therefore we will require additional numerical and laboratory experiments.</p></p><p><p>In practice, a flow through porous media is significantly more complex than the one-directional dominated flows considered in our numerical and laboratory column experiments. Around a well the flow is typically three-dimensional and largely radially dominated. We constructed two numerical domains to study the interactions between the cleanup of three square pores: one in a straight channel and one in a divergent channel to study the radial spread that would be experienced around a well. For a series of three dead-end pores, there was a 35% improvement by rapidly pulsed flow over steady flow in the straight channel and a 33% improvement in the divergent domain. The optimal frequency was different in the divergent flow even though the pores were the same size as in the previous study. Since the divergent channel reduced the flow velocity, the pulses reached the pores at a decreasing rate. Due to this divergence and the range of pore-sizes in a natural aquifer, implementation of rapidly pulsed flow should likely include a range of frequencies.</p></p><p><p>We concluded that the rapidly pulsed flow on the time scale of one-second would greatly enhance the cleanup of contaminated aquifers by P&T or VCW approaches. We measured significant improvements in the time to recovery. For our preliminary VCW experiment showed that rapidly pulsed pumping recovers 50% of the contaminant four times faster than steady pumping. P&T and VCW remediation typically use a steady flow; there are some methods that change the flow rate in P&T and other configurations, such as the VCW. These periodic changes in rate are on the scale of months to years. Some VCWs and air sparging technologies pulse oxygen, surfactants, and/or nutrients into the aquifer to oxidize, mobilize, or bioremediate the contaminants. As reviewed in chapter 6 in detail, all pulsing so far applied in remediation is on the time scale of a day or longer. Such low pulsing frequency does not produce sufficiently many deep sweeps to make a significant difference in cleaning dead-end pores.</p></p><p><p>Implementation of rapidly pulsed technology will utilize the same extraction and injection wells currently used in pump-and-treat remediation but will require replacement or significant modification of the pumps.</p></p><p><p>There are public health and financial implications of this research. In the dissertation conclusions section we reinterpret our numerical experiments with the multiple interacting dead-end pores and a divergent pass-through pore and laboratory experiments with a vertical circulation well chamber by calculating and plotting the ratio of times needed to reach a specified fraction recovered (specified cleanup level) in the steady and rapidly pulsed pumping modes, \tau_{s} / \tau_{p}. This ratio represents the speedup factor, i.e., the factor by which the time needed to reach the specified cleanup level with the conventional remediation (with steady pumping) would be reduced. From our experiments it appears that with the increasing level of targeted cleanup (contaminant fraction recovered), the speedup factor increases and may even exceed an order of magnitude. As we demonstrate in the dissertation conclusions section, this could translate into tens of billions of dollars in savings. Whether or not the laboratory speedup factors would hold in the field cannot be established without field-scale experiments.</p></p> / Dissertation

<p>As the human population continues to increase, the effects of land use change on streams and their watersheds will be one of the central problems facing humanity, as we strive to find ways to preserve important ecosystem services, such as drinking water, irrigation, and wastewater processing. This dissertation explores the effects of land use change on watershed nitrate concentrations, and on several biogeochemical ecosystem functions in streams, including nitrate uptake, ecosystem metabolism, and heterotrophic carbon processing. </p><p>In a literature synthesis, I was able to conclude that nitrate concentrations in streams in forested watersheds tend to be correlated with soil solution and shallow groundwater nitrate concentrations in those watersheds. Watershed disturbances, such as ice storms or clear-cutting, did not alter this relationship. However both urban and agricultural land use change increased the nitrate concentrations in streams, soil solution, and groundwater, and altered the correlation between them, increasing the slope and intercept of the regression line. I conclude that although the correlation between these concentrations allows for predictions to be made, further research is needed to better understand the importance of dilution, removal, and transformation along the flowpaths from uplands to streams.</p><p>From a multi-site comparison of forested, urban, and urban restored streams, I demonstrated that ecosystem functions like nitrate uptake and ecosystem metabolism do not change in a linear unidirectional way with increasing urbanization. I also showed that Natural Channel Design stream restoration as practiced at my study sites had no net effect on ecosystem function, except those effects that came from clearing the riparian vegetation for restoration construction. This study suggested further consideration is needed of the ecosystem effects of stream restoration as it was practiced at these sites. It also suggested that more study was needed of the effects of urbanization on ecosystem metabolism and heterotrophic processes in streams.</p><p>In a 16-month study of ecosystem metabolism at four sites along an urbanization gradient, I demonstrated that ecosystem metabolism in urban streams may be controlled by multiple separate effects of urbanization, including eutrophication, light, temperature, hydrology, and geomorphology. One site, with high nutrients, high light, and stable substrate for periphyton growth but flashy hydrology, demonstrated a boom-bust cycle of gross primary production. At another site, high benthic organic matter standing stocks combined with low velocities and high depths to create hypoxic conditions when temperature increased. I propose a new conceptual framework representing different trajectories of these effects based on the balance of increases in scour, thermal energy and light, eutrophication, and carbon loading. </p><p>Finally, in a study of 50 watersheds across a landscape urbanization gradient, I show that urbanization is correlated with a decrease in particulate carbon stocks. I suggest that an increase in dissolved organic matter quality may serve to compensate for the loss of particulate carbon as fuel for heterotrophic microbial activity. Although I saw no differences among watershed landuses in microbial activity per gram of sediment, there was a strong increase in the efficiency of microbial activity per unit organic sediment with increasing watershed urbanization. Ultimately, I hope that this research contributes to our understanding of stream ecosystem functions and the way land use change can alter these functions, with the possibility of better environmental management of urban streams in the future.</p> / Dissertation

How much groundwater flows to boreal streams depends on the relative contributions from each landscape unit (forested uplands, lakes, and peatlands) within a catchment along with its hydrogeologic setting. Although there is an understanding of the hydrologic processes that regulate groundwater outputs from individual landscape units to their underlying aquifers (both coarse- and fine-textured) in the boreal forest, less understood is how the topography, typology, and topology (i.e. hydrologic connectivity) of the landscape units regulates groundwater flow to streams. Improved understanding of groundwater-stream interactions in the Boreal Plain of Alberta and Saskatchewan is critical as this region is undergoing substantial environmental change from land cover disturbances for energy and forestry industries and climate change. This thesis determines groundwater-stream interactions during the autumn low-flow period in a 97 km2 glacial outwash sub-catchment of White Gull Creek Research Basin, Boreal Ecosystem Research and Modelling Site, Saskatchewan. The catchment (Pine Fen Creek) is comprised of a large (30 km2) valley-bottom peatland, two lakes, and jack pine (Pinus banksiana) uplands. The pine uplands are important areas of annual groundwater recharge for the catchment. Vertical hydraulic gradients (VHGs) show frequent flow reversals between the lakes and sand aquifer, and spatially diverse VHGs between the peatland and sand aquifer. Groundwater flow nets and lateral hydraulic gradients indicate the stream receives groundwater along its length. Isotopic samples of end members corroborate the hydrometric data. Catchment streamflow response during the 2011 low flow period was not simply the addition of net groundwater inputs from each landscape unit. Instead, the large size, valley-bottom position, and short water ‘memory’ of the peatland were the critical factors in regulation of catchment streamflow during low flow periods. Peatland hydrologic function alternated between a source and sink of runoff (surface and subsurface) to the stream, dependent on the position of the water table; a value of 0.15 m below peat surface was the critical functional tipping point. Given the high percentage of peatlands (21%) within the Boreal Plain, incorporating their runoff threshold is required in parameterizing runoff generation in hydrological models, and thus predicting impacts of peatland degradation and forest clearing on streamflow.

This thesis utilizes a distributed hydrologic model to predict hydrologic effects of Low Impact Development (LID), and also analyzes runoff from small sub-areas within the watershed. City planners and developers rely on accurate hydrologic models, which enable them to design flood-proof developments and effectively mitigate flooding downstream. Common hydrologic models use a lumped approach, which averages the physical characteristics of basins for model calculations, limiting their ability to estimate runoff within the basin. In contrast, distributed hydrologic models, which divide the watershed into a grid system, can be used to predict runoff at any location within the watershed. The fully distributed hydrologic model, VfloTM, is used to model stormwater runoff in The Woodlands, TX watershed, and to demonstrate the effectiveness of the master planned community. This thesis also suggests that a calibrated VfloTM model can accurately predict stormwater runoff from small sub-areas within a watershed.

<p>Groundwater has an important role in forging the composition of surface water, supplying nutrients crucial for the development of balanced ecosystems and potentially introducing contaminants into otherwise pristine surface water. Due to water-rock interactions radium (Ra) in groundwater is typically much more abundant than in surface water. In saline environments Ra is soluble and is considered a conservative tracer (apart for radioactive decay) for Ra-rich groundwater seepage. Hence in coastal environments, where mostly fresh groundwater seep into saline surface water, Ra has been the prominent tracer for tracking and modeling groundwater seepage over more than three decades. However, due to its reactivity and non-conservative behavior, Ra is rarely used for tracing groundwater seepage into fresh or hypersaline surface water; in freshwater, Ra is lost mostly through adsorption onto sediments and suspended particles; in hypersaline environments Ra can be removed through co-precipitation, most notably with sulfate salts. </p><p>This work examines the use of Ra as a tracer for groundwater seepage into freshwater lakes and rivers and into hypersaline lakes. The study examines groundwater-surface water interactions in four different environments and salinity ranges that include (1) saline groundwater discharge into a fresh water lake (the Sea of Galilee, Israel); (2) modification of pore water transitioning from saline to freshwater along their flow through sediments (pore water in sediments underlying the Sea of Galilee, Israel); (3) fresh groundwater discharge into hypersaline lakes (Sand Hills, Nebraska); and (4) fresh groundwater discharge into a fresh water river (Neuse River, North Carolina). In addition to measurement of the four Ra isotopes (<super>226</super>Ra, <super>228</super>Ra, <super>223</super>Ra, <super>224</super>Ra), this study integrates geochemical (major and trace elements) with additional isotopic tools (strontium and boron isotopes) to better understand the geochemistry associated with the seepage process. To better understand the critical role of salinity on Ra adsorption, this study includes a series of adsorption experiments. The results of these experiments show that Ra loss through adsorption decreases with increasing salinity, and diminishes in salinity as low as ~5% of the salinity of seawater. </p><p>Integration of the geochemical data with mass-balance models corrected for adsorption allows estimating groundwater seepage into the Sea of Galilee (Israel) and the Neuse River (North Carolina). A study of the pore water underlying the Sea of Galilee shows significant modifications to the geochemistry and Ra activity of the saline pore water percolating through the sediments underlying the lake. In high salinity environments such as the saline lakes of the Nebraska Sand Hills, Ra is shown to be removed through co-precipitation with sulfate minerals, its integration into barite (BaSO₄) is shown to be limited by the ratio of Ra:Ba in the precipitating barite. </p><p>Overall, this work demonstrates that Ra is a sensitive tracer for quantifying groundwater discharge even in low-saline environments. Yet the high reactivity of Ra (adsorption, co-precipitation, production of the short-lived isotopes) requires a deep understanding of the geochemical processes that shape and control Ra abundances in water resources.</p> / Dissertation

<p>This dissertation investigates the limnology of the southwestern Peruvian Amazon centered on the Madre de Dios department by examining first the geomorphology and then the ecology and biogeochemistry of the region's fluvial systems. </p><p>Madre de Dios, Peru is world renowned for its prolific biodiversity and its location within the Andes biodiversity hotspot. It is also a site of study regarding the development of the Fitzcarrald Arch and that feature's geomorphological importance as the drainage center for the headwaters of the Madeira River - the Amazon's largest tributary and as well as its role as a physical divider of genetic evolution in the Amazon. Though each of these has been studied by a variety of prominent researchers, the ability to investigate all the aspects of this unique region is hampered by the lack of a regional geomorphological map. This study aims to fill that gap by using remote sensing techniques on digital elevation models, satellite imagery and soil, geology and geoecological maps already in publication to create a geomorphological map. The resulting map contains ten distinct landform types that exemplify the dominance of fluvial processes in shaping this landscape. The river terraces of the Madre de Dios River are delineated in their entirety as well as the various dissected relief units and previously undefined units. The demarcation of the boundaries of these geomorphic units will provide invaluable assistance to the selection of field sites by future researchers as well as insights into the origin of the high biodiversity indices of this region and aid in planning for biodiversity conservation. </p><p>Secondly this study examines 25 tropical floodplain lakes along 300 km of the Manu River within the Manu National Park in the Madre de Dios department. Alternative stable state and regime shifts in shallow lakes typically have been examined in lakes in temperate and boreal regions and within anthropogenically disturbed basins but have rarely been studied in tropical or in undisturbed regions. In contrast this study focuses on a tropical region of virtually no human disturbance and evaluates the effects of hydrological variability on ecosystem structure and dynamics. Using satellite imagery a 23 yr timeline of ecological regime shifts in Amazon oxbow lakes or "cochas" is reconstructed. The study shows that almost 25% of the river's floodplain lakes experience periodic abrupt vegetative changes with an average 3.4% existing in an alternative stable state in any given year. State changes typically occur from a stable phytoplankton-dominated state to a short lived, <3 yr, floating macrophytic state and often occur independent of regional flooding. We theorize that multiple dynamics, both internal and external, drive vegetative regime shifts in the Manu but insufficient data yet exists in this remote region to identify the key processes. </p><p>To complete the investigation of tropical limnology the third study compares and contrasts the nutrient-productivity ration of floodplain and non-floodplain lakes globally and regionally. For over 70 years a strong positive relationship between sestonic chlorophyll-a (Chl-a) and total phosphorus (TP) has been established with phosphorus generally viewed as the most limiting factor to productivity. Most of these studies, however, have focused on northern, temperate regions where the lakes are typically postglacial, isolated and fed by small streams. Relatively little work has been done on floodplain lakes which are semi or permanently connected to the river. This study examines the relationship between nutrients and productivity in floodplain lakes globally through an extensive literature synthesis. Values for total phosphorus, total nitrogen and chlorophyll-a were collected for 523 floodplain lakes, represented by 288 data points while 551 data points were collected for 5444 non-floodplain lakes. Analysis revealed that globally, floodplain lakes do not show any significant difference in the total phosphorus/chlorophyll-a relationship from that found in non-floodplain lakes but significant differences are seen between tropical and temperate lakes. We propose that the term `floodplain' lake should serve as purely a geographical descriptor and that it is lacking as an ecological indicator. Instead factors such as precipitation seasonality, hydrological connectivity and regional flooding regimes are better indicators of high or low productivity in floodplain lakes.</p> / Dissertation

Natural and human-induced environmental changes have been altering the earth's surface and hydrological processes, and thus directly contribute to the severity of flood hazards. To understand these changes and their impacts, this research developed a GISbased hydrological and hydraulic modeling system, which incorporates state-of-the-art remote sensing data to simulate flood under various scenarios. The conceptual framework and technical issues of incorporating multi-scale remote sensing data have been addressed. This research develops an object-oriented hydrological modeling framework. Compared with traditional lumped or cell-based distributed hydrological modeling frameworks, the object-oriented framework allows basic spatial hydrologic units to have various size and irregular shape. This framework is capable of assimilating various GIS and remotely-sensed data with different spatial resolutions. It ensures the computational efficiency, while preserving sufficient spatial details of input data and model outputs. Sensitivity analysis and comparison of high resolution LIDAR DEM with traditional USGS 30m resolution DEM suggests that the use of LIDAR DEMs can greatly reduce uncertainty in calibration of flow parameters in the hydrologic model and hence increase the reliability of modeling results. In addition, subtle topographic features and hydrologic objects like surface depressions and detention basins can be extracted from the high resolution LiDAR DEMs. An innovative algorithm has been developed to efficiently delineate surface depressions and detention basins from LiDAR DEMs. Using a time series of Landsat images, a retrospective analysis of surface imperviousness has been conducted to assess the hydrologic impact of urbanization. The analysis reveals that with rapid urbanization the impervious surface has been increased from 10.1% to 38.4% for the case study area during 1974 - 2002. As a result, the peak flow for a 100-year flood event has increased by 20% and the floodplain extent has expanded by about 21.6%. The quantitative analysis suggests that the large regional detentions basins have effectively offset the adverse effect of increased impervious surface during the urbanization process. Based on the simulation and scenario analyses of land subsidence and potential climate changes, some planning measures and policy implications have been derived for guiding smart urban growth and sustainable resource development and management to minimize flood hazards.

In this study, I examined the effect of watershed urbanization on the invasion of alien woody species in riparian forests. This study was conducted in three major steps: 1) estimating the degree of watershed urbanization using impervious surface maps extracted from remote sensing images; 2) examining the effect of urbanization on hydrologic regime; and 3) investigating a relationship between watershed urbanization and ecosystem invasibility of a riparian forest. I studied twelve riparian forests along urban-rural gradients in Austin, Texas. Hydrologic regimes were quantified by transfer function (TF) models using four-year daily rainfall-streamflow data in two study periods (10/1988-09/1992 and 10/2004-09/2008) between which Austin had experienced rapid urbanization. For each study period, an impervious surface map was generated from Landsat TM image by a support vector machine (SVM) with pairwise coupling. SVM more accurately estimated impervious surface than other subpixel mapping methods. Ecosystem invasibilities were assessed by relative alien cover (RAC) of riparian woody species communities. The results showed that the effects of urbanization differ by hydrogeologic conditions. Of the study watersheds, seven located in a hillslope region experienced the diminishing peakflows between the two study periods, which are contrary to current urban hydrologic model. I attributed the decreased peakflows to land grading that transformed a hillslope into a stair-stepped landscape. In the rest of the watersheds, peakflow diminished between the two study periods perhaps due to the decrease in stormwater infiltration and groundwater pumpage that lowered groundwater level. In both types of watersheds, streamflow rising during a storm event more quickly receded as watershed became more urbanized. This study found a positive relationship between RAC and watershed impervious surface percentage. RAC was also significantly related to flow recession and canopy gap percentages, both of which are indicators of hydrologic disturbance. These results suggest that urbanization facilitated the invasion of alien species in riparian forests by intensifying hydrologic disturbance. The effects of urbanization on ecosystems are complex and vary by local hydrologeologic conditions. These results imply that protection of urban ecosystems should be based on a comprehensive and large-scale management plan.

In this study, Yuvacik Basin, which is located in southeastern part of Marmara Region of T&uuml / rkiye, is selected as the application basin and hydrologic modeling studies are performed for the basin. Basin is divided into three subbasins such as: Kirazdere, Kazandere, and Serindere and each subbasin is modeled with its own parameters. In subbasin and stream network delineation HEC-GeoHMS software is used and for the hydrologic modeling studies the new version of HEC-HMS hydrologic modeling software released in April 2006 is used. Modeling studies consist of four items: event-based hourly simulations, snow period daily simulations, daily runoff forecast using numerical weather prediction data, and runoff scenarios using intensity-duration-frequency curves. As a result of modeling studies, infiltration loss and baseflow parameters of each subbasin are calibrated with both hourly and daily simulations. Hourly parameters are used in spring, summer and fall seasons / daily parameters are used in late fall, winter and early spring (snowfall and snowmelt period) to predict runoff. Observed runoffs are compared with the forecasted runoffs that are obtained using MM5 grid data (precipitation and temperature) in the model. Goodness-of-fit between forecasted and observed runoffs is promising. Hence, the model can be used in real time runoff forecast studies. At last, runoffs that correspond to different return periods and probable maximum precipitation are predicted using intensity-duration-frequency data as input and frequency storm method of HEC-HMS. These runoffs can be used for flood control and flood damage estimation studies.

This study aims to investigate tectonic activity levels and development stages of the tectonic and hydrologic basin areas located on western part of the main trace of the North Anatolian Fault Zone (NAFZ) using quantitative measurement techniques. The basins investigated are Bolu, Yeni&ccedil / aga, D&ouml / rtdivan, &Ccedil / erkes, Ilgaz and Tosya. The methodology includes application of six morphometric indices (Basin Shape, Hypsometric curve and Hypsometric Integral, Sinuosity of Mountain Fronts, Stream Length Gradient Index, Valley width to height ratio, and Asymmetry Factor) to Digital Elevation Model (DEM) of the region generated from 1:25000 scale topographic maps. The analyses indicate that the basins located in the study area have different characteristics of tectonic activity. According to the results of the applied indices relative order of the activity for tectonic basins is, in decreasing order, Bolu, Tosya, Ilgaz, &Ccedil / erkes, Yeni&ccedil / aga and D&ouml / rtdivan. For hydrologic basins, on the other hand, the same order is observed except for a swap in &Ccedil / erkes and Yeni&ccedil / aga basins. Among the basins located to the north of the NAFZ, the activity decreases eastward whereas to the south the fault zone it decreases towards the west.