Simulating Thermal Stress in Rhode Island Coldwater Fish Habitat Using SWAT

Climate studies have suggested that inland stream temperatures and streamflow will increase over the next century in New England, thereby putting aquatic species sustained by coldwater habitats at risk. To effectively aid these ecosystems it has become ever more important to recognize historical water quality trends and anticipate the future impacts of climate change. This thesis uses the Soil and Water Assessment Tool (SWAT) to simulate historical and future streamflow and stream temperatures within three forested, baseflow driven watersheds in Rhode Island. The results provide a site-specific method to fisheries managers trying to protect or restore local coldwater habitats. The first manuscript evaluated two different approaches for modeling historical streamflow and stream temperature with the Soil and Water Assessment Tool (SWAT), using i) original SWAT and ii) SWAT plus a hydroclimatological model component that considers both hydrological inputs and air temperature effects on stream temperature (Ficklin et al., 2012). Model output was used to assess stressful events at the study site, Cork Brook, RI, between 1980-2009. Stressful events for this study are defined as any day where high or low flows occur simultaneously with stream temperatures exceeding 21 ̊C, the threshold at which brook trout (Salvelinus fontinalis), a coldwater fish species, begins to exhibit physiological stress. SWAT with the hydroclimatological component performed better during calibration (Nash-Sutcliffe Efficiency (NSE) of 0.93, R of 0.95) compared to original SWAT (NSE of 0.83, R of 0.93). Between 1980-2009, the number of stressful events increased by 55% and average streamflow increased by 60% at the study site. This chapter supports the application of the hydroclimatological SWAT component and provides an example method for assessing stream conditions in southern New England. The second manuscript uses the original SWAT model to simulate both historical and future climate change scenarios for Cork Brook and two other watersheds, the Queen River and Beaver River, in Rhode Island. These three sites were selected primarily due to their pristine aquatic habitat, data availability and existing interest in natural resource conservation by local non-profit and government groups. Similar to the first manuscript, this study analyzed model output to identify stressful events for brook trout. Results indicate that the Queen River has historically had the highest percent chance (6.4 %) that a stressful event would occur on any given day and Cork Brook had the lowest percent chance (4.4%). In future climate scenarios coldwater fish species such as brook trout will be increasingly exposed to stressful events. The model predicted that between 2010-2099 stream temperatures in all watersheds will increase by 1.6  ̊C under the low emission scenario or 3.4  ̊C under the high emission scenarios. The model also predicted that high stream temperatures in the Cork Brook watershed will occur two months earlier in the year by the end of the century. Between 2010 and 2099, discharges increased by an average of 20% under the low emissions scenario and 60% under the high emissions scenario. The percent chance of a stressful event increased between historical simulations and future simulations by an average of 6.5% under low emission scenarios and by 14.2% under high emission scenarios. These results indicate that climate change will have a negative effect on coldwater fish species in these types of ecosystems, and that the resiliency of local populations will be tested as stream conditions will likely become increasingly stressful. The purpose of this Master’s thesis was to gain a better understanding of stream conditions within Rhode Island’s coldwater fish habitat using SWAT. It was successfully shown that SWAT can be used to simulate both historical and future climate scenarios in forested, baseflow driven watersheds in Rhode Island. Moreover, a functional approach to analyzing model output is to identify thermally stressful events for coldwater species. As the demand for water quality and quantity increases for wildlife and human consumption over the next century, new evaluation techniques will help anticipate unprecedented challenges due to climate change.


LIST OF TABLES
Shows the percent chance that of the 3,653 days per each decade and 10,958 days between 1980-2009, a day with any type of stress will occur, a day with flow stress will occur, a day with temperature stress will occur and the percent chance of a stressful event. .   (Ficklin) component. Shows the percent chance that of days with any type of stress, a day will be stressful due to flow, percent chance that a day will be stressful due to high stream temperature, percent chance that a both stresses will occur on the same day and result in an event..

INTRODUCTION
Stream temperatures in the New England region of the United States have been increasing steadily over the past 100 years [1]. Over the next century, freshwater ecosystems in New England are expected to experience continued increase in mean daily stream temperatures and an increase in the frequency and magnitude of extreme flow events due to warmer, wetter winters, earlier spring snowmelt, and drier summers [1][2][3][4][5][6][7][8][9]. As the spatial and temporal variability of stream temperatures play a primary role in distributions, interactions, behavior, and persistence of coldwater fish species such as trout [7,[10][11][12][13][14][15][16], it has become increasingly important to understand historical patterns of change so that a comparison can be made when projecting the future effects of climate changes on local ecosystems.
This study used the Soil and Water Assessment Tool (SWAT) [17] to generate historical streamflow and stream temperature data, followed by an assessment of the frequency of "stressful events" affecting the Rhode Island native brook trout (Salvelinus fontinalis). Brook trout, a coldwater salmonid, is a species indicative of high water quality and is also of interest due to recent habitat and population restoration efforts by local environmental groups and government agencies [18,19].
This fish typically spawns in the fall, and lays eggs in redds (nests) deposited in gravel substrate. The eggs develop over the winter months and hatch from late winter and early spring. However, the life-cycle of brook trout is heavily influenced by the degree and timing of temperature changes [11,20]. High stream temperatures cause physical stress including slowed metabolism and decreased growth rate, adverse effects on critical life-cycle stages such as spawning or migration triggers, and in extreme cases, mortality [7,[21][22][23][24]. Distribution is also affected as coldwater fish actively avoid water temperatures that exceed their preferred temperature by 2-5 ˚C [25,26]. Studies have shown that optimal brook trout water temperatures remain below 20 ˚C. Symptoms of physiological stress develop at approximately 21 ˚C [21] and temperatures above 24 ˚C have been known to cause mortality in this species [11].
Flow regime is another central factor in maintaining the continuity of aquatic habitat throughout a stream network [22,[27][28][29][30][31][32]. While temperature is often cited as the limiting factor for brook trout, the flow regime has considerable importance [33].
Alteration of the flow regime can result in changes in the geomorphology of the stream, the distribution of food producing areas as riffles and pools shift, reduced macroinvertebrate abundance and more limited access to spawning sites or thermal refugia [20,34,35].    [36] and in New England [42]. Lastly, the generated stream temperature and streamflow data are analyzed to understand the frequency of stressful conditions for coldwater habitat in Cork Brook.
Results provide a site-specific approach to identifying critical areas in watersheds for best management practices with the goal of maintaining or improving water quality for both human consumption and aquatic habitat. continue as expected, decisions to protect a habitat based on its known resilience may have a large impact on how resources and preservation efforts will be allocated.  [53,54].

MATERIALS AND METHODS
The SWAT Calibration and Uncertainty Program (SWAT-CUP), Sequential Uncertainty Fitting Version 2 (SUFI-2) [55,56], was used to conduct sensitivity analysis, calibration and model validation on stream discharge from the output hydrograph. Performance was measured using coefficient of determination and Nash-Sutcliffe Efficiency (NSE) and percent bias (PBIAS). Coefficient of determination (R 2 ) identifies the degree of collinearity between simulated and measured data and NSE was used as an indicator of acceptable model performance. R 2 values range from 0 to 1 with a larger R 2 value indicating less error variance. NSE is a normalized statistic that determines the relative magnitude of the residual variance compared to the measured data variance [57]. NSE ranges from -∞ to 1; a value at or above 0.50 generally indicates satisfactory model performance [58]. This evaluation statistic is a commonly used objective function for reflecting the overall fit of a hydrograph.
Percent bias is the relative percentage difference between the averaged modeled and measured data time series over (n) time steps with the objective being to minimize the value [59]. where Tw.initial is the weighted average of the contributions within the subbasin and from the upstream subbasin, Tw.upstream is the temperature of water entering the subbasin (˚C), Qoutlet is the streamflow discharge at the outlet of the subbasin (m 3 d -1 ); where Tair is the average daily temperature (˚C), K(1/h) is a bulk coefficient of heat transfer ranging from 0-1, TT is the travel time of water through the subbasin (hours) and ε is an air temperature addition coefficient. The ε coefficient is an important component because it allows the water temperature to rise above 0 ˚C when the air temperature is below 0 ˚C. If air temperature is less than 0 ˚C, the model will set the stream temperature to 0.1 ˚C. These details are further discussed in the results section of the paper. The source code for the Ficklin  indicators because of their common use [63][64][65] and ecohydrological importance to brook trout. The most critical period for the species is typically the lowest flows of late summer to winter and a base flow of less than 25% is considered poor for maintaining quality trout habitat [11,66]. A Q75 represents the lowest 25% of all daily flow rates and a Q25 exceedance characterizes the highest 25% of all daily flow rates.
Flow-exceedance probability, or flow-duration percentile, is a well-established method and generally computed using the following equation: where P is the probability that a given magnitude will be equaled or exceeded (percent of time), M is the ranked position (dimensionless) and n is the number of events for period of record [65]. For the stressful event analysis, the exceedance probability and average daily stream temperature for each date were identified. If the day fell into the Q25 or Q75 percentile, and if the stream temperature was greater than 21 ˚C, then the day was tagged as being a thermally stressful event.

Model Calibration and Validation: Stream Discharge
The initial model was run for the entire period of precipitation and rainfall data availability  Table 1, and the statistical results of calibration and validation are shown in Table 2.

Model Calibration and Validation: Stream Temperature
Once the initial SWAT model was satisfactorily calibrated and validated for discharge the hydroclimatological component was added to the SWAT files and the model was run using both the basic SWAT approach and the revised stream temperature program. The hydroclimatological temperature model had no effect on stream discharge therefore the discharge was not re-calibrated. The simulated stream temperature was manually calibrated by changing several variables in the basin file associated with the hydroclimatological component: K, lag time and seasonal time periods in Julian days ( Table 3). The K variable represents the relationship between air and stream temperature and ranges from 0 to 1. As K approaches 1, the stream temperature is approximately the same as air temperature and as K decreases the stream water is less influenced by air temperature [36]. The temperature outputs are also sensitive to the lag time, a calibration parameter corresponding to the effects of  The above parameters produced satisfactory calibration statistics, as summarized in Table 4. During the winter and spring, the stream temperature is roughly the same as the air. In the summer and fall, the K value is decreased and the stream temperature is less affected by air temperature. This may be due to extensive tree shading [36], which is in agreement for Cork Brook as it is a relatively small watershed that is predominantly forested [68]. The lag time is also relatively short throughout the year although it varies with the seasons. Not surprisingly, the lag time for hydroclimatological calibration is not far from the surface and groundwater delay parameters set during stream discharge calibration. Modeled versus observed stream temperature for both the basic SWAT and hydroclimatological approach is shown in

Stream Conditions and Stressful Event Analysis
The occurring [69,70]. A large scale regional study [1]   As water temperatures increase due to global warming, brook trout may benefit from sustained flows which will prevent stream temperatures from raising further and help ensure that downstream habitat remains connected to headwaters. On the other hand, a sustained increase in flow magnitude can change the geomorphology and may not be beneficial for aquatic species during the spawning season when flows are normally lower [30]. An increase in stream discharges during the low flow season may put redds at risk of destruction from sedimentation or sheer velocity. Changes in streamflow magnitude may also increase turbidity or redistribute riffle and pool habitat throughout the stream reach. This may decrease the availability of suitable habitat as brook trout prefer stream reaches with an approximate 1:1 pool-riffle ratio [11]. Pool and riffle redistribution can also affect the type and quantity of local macroinvertebrate populations. Since warming temperatures will have an impact on body condition as fish enter the winter months, the available food supply can become an even more critical factor as the climate changes.
To identify the number of stressful events simulated by the model, output data were analyzed by decade (1980-1989, 1990-1999 and 2000-2009) and over the entire 30 year period. The percent chance that a stressful event would occur on any given day throughout the time period was also calculated. These results are shown in Table 5 below. The percentile because lower, slower flows are exposed to air longer causing them to increase or decrease in temperature more easily. The fact that there were no stressful events above the Q97 flow percentiles is most likely attributed to groundwater inputs.
During the dry or low flow periods in summer and fall, baseflow will be the primary input to groundwater fed streams. Because the hydroclimatological model component takes the groundwater temperature into consideration (equation 1), the lowest discharge amounts the model simulates will likely be baseflow driven and therefore cooler than water that is continuously exposed to ambient air temperatures. This is good news for coldwater fish species which spawn in the fall or those that begin their migration into headwaters during the low flow season as the chances of exposure to high temperatures are lessened from groundwater contributions.     SWAT model was used to generate historical and future stream temperature and streamflow data, followed by an assessment of the frequency of "stressful events" affecting the Rhode Island native brook trout. Brook trout, a coldwater salmonid, is a species indicative of high water quality and is also of interest due to recent habitat and population restoration efforts by local environmental groups and government agencies [29,30]. This fish typically spawns in the fall, and lays eggs in redds (nests) deposited in gravel substrate. Eggs develop over the winter months and hatch from late winter to early spring [11,12,31]. However, the life-cycle of brook trout is heavily influenced by the degree and timing of temperature changes. High stream temperatures cause physical stress including slowed metabolism and decreased growth rate, adverse effects on critical life-cycle stages such as spawning or migration triggers, and in extreme cases, mortality [7,10,[32][33][34][35]. Distribution is also affected as coldwater fish actively avoid water temperatures that exceed their preferred temperature by 2-5 ˚C [36,37]. Studies have shown that optimal brook trout water temperatures are below 20

˚C, symptoms of physiological stress develop at approximately 21 ˚C [33] and
temperatures above 24 ˚C have been known to cause mortality in this species [12].
Flow regime is another central factor in maintaining the continuity of aquatic habitat throughout a stream network [35,[38][39][40][41][42][43]. While temperature is often cited as the limiting factor for brook trout, the flow regime has considerable equal importance [44]. headwater subbasins, the Queen River and Beaver River, were selected as study sites due primarily to their pristine aquatic habitat (Figure 1). A third pristine watershed, Cork Brook, was chosen for the study because of its association with the Scituate Reservoir which supplies drinking water to the City of Providence. Existing scientific studies have been conducted on water quality in the Wood-Pawcatuck watersheds [47][48][49] and its subbasins [50][51][52][53]. Potential brook trout habitat restoration areas in Rhode Island [29] have also been researched. These studies have provided information regarding regional water resources. SWAT, however, has never been utilized to study climate change effects on flow and temperature conditions at a basin-wide scale in these Rhode Island watersheds.
Results provide a site-specific approach for watershed managers trying to determine the types and distribution of future habitat risks to coldwater species. As the demands for water quality and quantity increase for wildlife and human consumption over the next century, new evaluation techniques will help anticipate and solve unprecedented challenges. In the Wood-Pawcatuck and Cork Brook watersheds, the anticipated challenges may include an increase in stressful conditions. Results indicate that under both high and low emission greenhouse gas scenarios, coldwater fish species such as brook trout will be increasingly exposed to stressful events. Percent

MATERIALS AND METHODS
Three gauged watersheds were studied to achieve the objective: Queen River,  [17,64]: Where (TW) represents average daily water temperature (˚C), (Tair) represents average daily air temperatures (˚C). Time (t) and lag (δ) are in days. Water temperatures follow air temperatures closely, the time lag for a shallow stream is expected to be on the order of a few hours due to the thermal inertia of the water [64].
The average relationship indicates that when the daily air temperature is close to 0 ˚C that the water will be approximately 5 ˚C warmer. When the daily air temperature is below 20 ˚C the water temperature is likely to be greater than the air temperature [64].
The Rhode Island Geographic Information System (RIGIS) database is the main source for the spatial data used as model inputs [65].  [73]. NSE ranges from -∞ to 1; a value at or above 0.50 generally indicates satisfactory model performance [74]. This evaluation statistic is a commonly used objective function for reflecting the overall fit of a hydrograph.
Percent bias is the relative percentage difference between the averaged modeled and measured data time series over (n) time steps with the objective being to minimize the value [75].    Upon model calibration, validation, and incorporation of climate change variables, output data for both model versions were processed to predict the occurrence of stressful conditions in all three watersheds from 1980-2099. As previously discussed, a stressful event for this study is defined as any day where both temperature and flow extremes occur. This study used the Q25 and Q75 flow exceedance percentiles as indicators because of their common use [76][77][78] and ecohydrological importance to brook trout. The most critical period for the species is typically the lowest flows of late summer to winter and a base flow of less than 25% is considered poor for maintaining quality trout habitat [12,44]. A Q25 exceedance characterizes the highest 25% of all daily flow rates and Q75 represents the lowest 25% of all daily flow rates. Flow-exceedance probability, or flow-duration percentile, is a well-established method and generally computed using Equation 2: where P is the probability that a given magnitude will be equaled or exceeded (percent of time), M is the ranked position (dimensionless) and n is the number of events for period of record [78]. For the stressful event analysis, the exceedance probability and average daily stream temperature for each date were identified. If the day fell into the Q25 or Q75 percentile, and if the stream temperature was greater than 21˚C, then the day was tagged as being a thermally stressful event.

Model Calibration and Validation
Each model was run for the entire period of precipitation and rainfall data availability    Table 2, and the statistical results of calibration and validation are shown in Table 3 and Table 4.  [79,80]. Alpha-bnk (bankflow) was another sensitive parameter which is simulated with a recession curve like that used for groundwater.
For this parameter, a high value at all three sites indicates a flat recession curve, which is similar to the alpha-bf value that specifies a slow response to drainage. The threshold depth of groundwater in the shallow aquifer (GWQMN) is small and very similar between all three models, less than a meter within each. This is the threshold water level in the shallow aquifer for groundwater contribution to the main channel to occur. There were minor differences in soil parameters. Available water content was relatively increased at the Cork Brook and Queen River sites and the hydraulic conductivity at Cork Brook is relatively decreased. Since groundwater accounts for the majority of stream discharge at all sites, the sensitivity of soil and groundwater parameters was expected. Other factors reflect the size differences between the watersheds. Cork Brook is smaller than the other two and has a lower surface lag time, groundwater delay and lower slope length.  Table 3. Statistical results of streamflow calibration produced by SWAT-CUP using the parameters listed in Table 1.

Stressful Event Analysis: Historical
The modeled average daily stream temperature was nearly the same at all three sites. The average daily discharge, however, was different at all three sites and corresponded to watershed area, with the highest discharge within the Queen River (largest watershed) and the lowest discharge within Cork Brook (smallest watershed) (Table 5). This is in agreement with the observed data in that the Queen River had the highest discharge for the years on record at the USGS Gauge followed by the Beaver River and Cork Brook. The calibrated model for each watershed was first run over the entire thirty-year period (1980-2009) ( Table 5) to understand the percent chance that a stressful event will occur on a given day. Of the three study sites, the Queen River had the highest percent chance that a stressful event would occur on any given day and the Beaver River had the lowest percent chance (Table 6).  Table 6: Stressful event analysis of SWAT simulation for the three study sites. Shows the percent chance that of the 10,958 days between 1980-2009, a day with any type of stress will occur, a day with flow stress will occur, a day with temperature stress will occur and the percent chance of an event. The frequency of stress events in the three watersheds are similar (Table 6).

Date
Cork Brook and the Beaver River have nearly the same chance of days with Q25 or Q75 flow. The chance of a Q25 or Q75 occurring in the Queen River is only 0.8% higher than that in the other two. Likewise, the chances of any type of stress occurring within the maximum and minimum watersheds vary by just 1.1%. One difference between Cork Brook and the Pawcatuck watersheds is the number of days with stream temperatures greater than 21 ˚C. The Beaver River and the Queen River have the same number of days with temperature stress because the air temperature for each model was collected from the same weather station. The number of days with stream temperature greater than 21 ˚C at Cork Brook is 46% higher than the Pawcatuck watersheds. This may be attributed to the low discharge levels at Cork Brook (0.081 m 3 /sec) because lower, slower flows are exposed to air longer causing them to increase or decrease in temperature more (i.e. a shorter lag time (Equation 1)). This interpretation is illustrated in Figures 5, 6

Future Projections: Stream Discharge and Stream Temperature
The modeled average daily stream temperature and average daily stream discharge increased at all sites for both low and high CO2 emission scenarios due to warmer ambient air temperature and change in the timing and magnitude of precipitation (Table 7, 8 and 9). New England is predicted to experience a warmer and wetter climate due to global warming [3]. Since 1970 in Rhode Island the average maximum and minimum air temperatures have increased by 1.2 ˚C annually, and by 2020-2099 it is expected that there will be hotter summers with 12-44 more days above 50 ˚C in Rhode Island [26]. Annual precipitation has also increased 6-11%. By 2020-2099, annual precipitation averages are predicted to rise by 18-20% and a twofold increase in extreme precipitation events is expected to occur. A decrease in snow cover is also projected and Rhode Island may have 20-32 fewer snow covered days [26]. shown an upward trend likely linked to increasing precipitation [81] and climate change may be impacting storage by increasing the volume of water held in groundwater or as soil moisture within the basin. When storage is exceeded, the upper streamflow quantiles may be affected [82]. Brook trout can benefit from increased baseflow. Groundwater inflow can cool stream water [83], especially when flows are lower in the summer months [84]. Brook trout rely on groundwater seeps as refugia from increased stream temperatures and to keep developing embryos submerged in cool water [12].
An increase in stream temperature and streamflow was also seen in Cork Brook        As water temperatures increase due to global warming, brook trout may benefit from sustained flows which will prevent stream temperatures from rising further and help ensure that downstream habitat remains connected to headwaters. From this perspective, the Beaver River and Cork Brook may provide better future trout habitat in comparison to the Queen River, which saw little change to the shape of the rating curve. On the other hand, a sustained increase in flow magnitude can change the geomorphology and may not be beneficial for aquatic species during the spawning season when flows are historically lower [41]. An increase in stream discharges during the low flow season may put nests at risk of destruction from sedimentation or sheer velocity. Changes in streamflow magnitude may also increase turbidity or redistribute riffle and pool habitat throughout the stream reach. This may decrease the availability of suitable habitat as brook trout prefer stream reaches with an approximate 1:1 poolriffle [12]. Pool and riffle redistribution can also affect the type and quantity of local macroinvertebrate populations. Since warming temperatures will have an impact on body condition as fish enter the winter months, the available food supply can become an even more critical factor as the climate changes. ˚C [12]. Higher temperatures earlier in the spring will mean that fish experience physiological stress sooner and may not be able to survive until the spawning period in late fall when stress will be relieved by cooler temperatures. Additionally, because brook trout avoid warmer water and are rarely found in streams with 60 days mean temperatures above 20 ˚C [7,33], changes to the temporal distribution of stream temperatures will likely have an effect on the spatial distribution of trout [7,[10][11][12][13][14][15][16].

Future Projections: Stressful Events
The results of the stressful event analysis are summarized in Table 10     watersheds. This is not to say that coldwater habitat restoration is not worthwhile in the Queen River, rather that more effort will be needed to restore or maintain brook trout populations in this watershed.  [87] and in New England [88]. Since the hydroclimatological model component takes the groundwater temperature into consideration, the stream reach will receive inputs that are less exposed to ambient air and therefore cooler during the summer and slightly warmer than the air during the winter. Using a SWAT model with this component may produce more accurate stream temperature results in streams that are baseflow driven.
The purpose of this study was to gain a better understanding of the effects of climate change on coldwater habitat using SWAT. We successfully showed that SWAT can be used to simulate both historical and future climate scenarios in forested, baseflow driven watersheds in Rhode Island. Moreover, thermally stressful event identification is a functional approach to analyzing model. The results indicate that climate change will have a negative effect on coldwater fish species in these types of ecosystems, and that the resiliency of local populations will be tested as stream conditions will likely become increasingly stressful.

Review of the Problem
The temporal and spatial variability of stream temperature and stream flow are two of the primary controls on the distribution and abundance of aquatic organisms.
Likewise, they are important parameters for determining the suitability of water resources for human use. Climate change is anticipated to have effects on aquatic ecosystems in the New England region of the USA. Evidence suggests that these impacts will include warming stream temperatures and changes to the flow regimes of inland freshwater resources. The consequences are expected to result in the reduced viability of aquatic populations and loss of habitat connectivity.
The site-specific effects of climate change on Rhode Island's inland coldwater habitats is not well studied in the Beaver River, Queen River or Cork Brook watersheds. Furthermore, hydrological models have not been used to analyze the effects of climate change on streamflow and stream temperature on Rhode Island brook trout (Salvelinus fontinalis) populations. This thesis approached these problems using the Soil and Water Assessment Tool (SWAT) to generate streamflow and stream temperature data within these three forested, baseflow driven watersheds in Rhode Island. The problem was also approached using a site-specific method to analyze the quality of aquatic habitat and its suitability for native coldwater fishes. The method identified "thermally stressful events" which, for the purposes of this study, are defined as any day where Q25 or Q75 flows occur simultaneously with stream temperatures >21˚C and brook trout are physiologically stressed.
The model output data were assessed to determine the number of incidences over a given time period that a day with high or low flows (Q25 or Q75) occurred, that a day with high stream temperatures (>21˚C) occurred, that any type of stress occurred, and the number of days that a stressful event occurred. The percent chance that a condition would occur was also calculated.
This thesis was written in two parts using similar but separate methodology.

Manuscript 1, titled "Assessing Thermally Stressful Events in RI Coldwater Fish
Habitat Using Swat Model" was conducted using SWAT with an added hydroclimatological component to assess the historical conditions in Cork Brook.

Manuscript 2, titled "Climate Change Induced Thermal Stress in Coldwater Fish
Habitat Using SWAT" was conducted using original SWAT with added climate change scenarios to assess both historical and future conditions in all three watersheds.   (Ficklin) component. Shows the percent chance that of days with any type of stress, a day will be stressful due to flow, percent chance that a day will be stressful due to high stream temperature, percent chance that a both stresses will occur on the same day and result in an event.  The initial intent of this project was to incorporate the hydroclimatological component into all three watershed models. Due to limited stream temperature data, however, it was not possible to calibrate the hydroclimatological component into the Beaver River and Queen River models. The calibration attempts for the Beaver River and the Queen River are included in this appendix and shown below.