Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed

Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed

Prepared for Water Security Agency of as part of the Natural Resource Canada Research Project Topic 3.3 – Case Studies of Mining Sector Adaptation Actions

By V. Wittrock

Saskatchewan Research Council Environment Division

SRC Publication No. 13462-5E13

September 2013

1 SRC Pulbication No 13462-5E13

LIMITED

Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed

Prepared for Water Security Agency of Saskatchewan as part of the Natural Resource Canada Research Project Topic 3.3 – Case Studies of Mining Sector Adaptation Actions

By V. Wittrock

Saskatchewan Research Council Environment Division

SRC Publication No. 13462-5E13

September 2013

Saskatchewan Research Council 125 – 15 Innovation Blvd. , SK S7N 2X8 Tel: 306-933-5400 Fax: 306-933-7817

Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013

Abstract Climate extremes are common on the . Droughts and floods can occur in the same year and can last multiple years. Preparedness for these events can assist to decrease or avoid the potential costs associated with negative impacts caused by these events. The potash mining industry in the Qu’Appelle River Watershed is relatively new and as such it has not had to adapt to longer duration events. Therefore, utilizing the information provided will assist the industry with their risk management strategies. These include whether adequate water supply is available for longer duration droughts or retention pond structures are adequate for many years of excessive moisture conditions.

The purpose of this report is to examine the climate of the Qu’Appelle River Watershed over the last 110 years. This information will assist in improving the planning and preparation for future extreme drought and excessive moisture events by the potash industry. The objectives are to:  Develop temperature and precipitation databases based on monthly values for the study area and surrounding region  Develop databases and characterize the intensity, duration, frequency and spatial pattern of the events for study area and surrounding region using various climatic indices including the Palmer Drought Severity Index, the Standardized Precipitation Index and the Standardized Precipitation and Evapotranspiration Index.

The last 15 years have highlighted the extremes with intense drought in the early 21st century (1999-2003) to extreme excessive moisture in the later part of the first decade of the 21st century (2010-2011). These events were compared with the drought events (1930s, 1940s and 1961) and excessive moisture periods that occurred in the 1950s and late 1960s to early 1970s. Therefore knowledge of historic extreme climatic events along with other indicators of future extremes assists with adapting to future extreme events.

SRC Publication No. 13462-5E13 i Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed

ii SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013

Table of Contents

Abstract ...... i Introduction ...... 1 Purpose and Objectives...... 3 Data and Methods ...... 3 Temperature and Precipitation Trends ...... 6 Temperature Trends ...... 6 Annual Temperature Trends ...... 7 Seasonal Temperature Trends ...... 7 Winter ...... 8 Spring ...... 8 Summer ...... 8 Autumn ...... 9 Precipitation Trends ...... 9 Yearly Precipitation Trends ...... 9 Seasonal Precipitation Trends ...... 10 Winter ...... 10 Spring ...... 11 Summer ...... 12 Autumn ...... 13 Climate Indices ...... 14 Palmer Drought Severity Index ...... 14 Temporal Patterns ...... 14 Spatial Patterns ...... 15 Drought ...... 16 Excessive Moisture ...... 16 Standardized Precipitation Evapotranspiration Index ...... 16 Temporal Patterns ...... 16 Spatial Patterns ...... 17 Drought ...... 17 Excessive Moisture ...... 17 Standardized Precipitation Index ...... 18 Temporal Patterns ...... 18 Spatial Patterns ...... 18 Drought ...... 18 Excessive Moisture ...... 18 Conclusions and Recommendations ...... 19 Acknowledgements ...... 20 References ...... 21

SRC Publication No. 13462-5E13 iii Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed

Figures

Figure 1 The number of natural catastrophes worldwide………………………...………………………...1 Figure 2 Major Natural Catastrphes in Caanda and USA in 2012………………………………………….2 Figure 3 Palliser Triangle in the Canadian Prairies………………………………………………………...3 Figure 4 Approximate locations of climate stations and potash mines in and around the Qu’Appelle River Watershed…………………………………………………...………………………………………………6 Figure 5 Annual Precipitation Departures from the 1971-2000 Average…………………………………10 Figure 6 Winter Precipitation Departures from the 1971-2000 Average……………………………….…11 Figure 7 Spring Precipitation Departures from the 1971-2000 Average……………………………….…12 Figure 8 Summer Precipitation Departures from the 1971-2000 Average………………………………..13 Figure 9 Autumn Precipitation Departures from the 1971-2000 Average…………………………..……13 Figure 10 Palmer Drought Severity Index (1901-2005)………………………………………………..…15 Figure 11 Standardized Precipitation Evapotranspiration Index (1901-2011)……………………..…...... 17 Figure 12 Standardized Precipitation Index (1902-2005)…………………………………………………18

Tables

Table 1 PDSI, SPI, SPEI Classifications ...... 5 Table 2 1971-2000 Annual Average Temperature for Selected Climate Station Locations...... 7 Table 3 Maximum and Minimum Values of PDSI, SPEI and SPI in the Qu’Appelle River Watershed....14

iv SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013

Appendix A – Temperature Trends

Figure A-1 Annual Average Temperature Departures from the 1971-2000 Average (Regina & , Indian Head & , Moosomin & Outlook)...... 25

Figure A-2 Minimum Annual Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 26

Figure A-3 Maximum Annual Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 27

Figure A-4 Winter Average Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 28

Figure A-5 Winter Minimum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 29

Figure A-6 Winter Maximum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 30

Figure A-7 Spring Average Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 31

Figure A-8 Spring Minimum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 32

Figure A-9 Spring Maximum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 33

Figure A-10 Summer Average Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 34

Figure A-11 Summer Minimum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 35

Figure A-12 Summer Maximum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 36

Figure A-13 Autumn Average Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 37

Figure A-14 Autumn Minimum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 38

Figure A-15 Autumn Maximum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 39

SRC Publication No. 13462-5E13 v Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed

Appendix B – Precipitation Trends

Figure B-116 Annual Precipitation Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 43

Figure B-2 Winter Precipitation Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 44

Figure B-3 Spring Precipitation Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 45

Figure B-4 Summer Precipitation Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 46

Figure B-5 Autumn Precipitation Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) ...... 47

Appendix C – Climate Indices – Spatial Analysis of Qu’Appelle River Watershed

Figure C-1 Palmer Drought Severity Index - 10 extreme years of moisture deficit conditions ...... 51

Figure C-2 Palmer Drought Severity Index - 10 extreme years of moisture surplus conditions ...... 53

Figure C-3 Standardized Precipitation Evapotranspiration Index - 10 extreme years of moisture deficit conditions ...... 55

Figure C-4 Standardized Precipitation Evapotranspiration Index - 10 extreme years of moisture surplus conditions ...... 57

Figure C-5 Standardized Precipitation Index - 10 extreme years of moisture deficit conditions ...... 59

Figure C-6 Standardized Precipitation Index - 10 extreme years of moisture surplus conditions ...... 61

vi SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013

Introduction Climate extremes are a common occurrence on the Canadian prairies. Both droughts and floods have occurred, sometimes in the same year. These extreme events can last for a relatively short duration but they can also be multi-year occurrences. The multi-year events can have more severe impacts than short term or daily events, and therefore, require more extreme adaptation actions and preparedness.

The numbers of natural catastrophes worldwide have been increasing. In the early 1980s there were generally less than 400, since the mid-1990s the number has increased to more than 600 and in 2007 more than 1000 worldwide were documented (Figure 1). In 2012, Munich RE categorized more than 800 events occurred worldwide. Many of these affected North America and the Canadian prairies (Figure 2).

Figure 1 The number of natural catastrophes worldwide as defined by Munich RE since 1980 (Munich RE 2013)

The frequency of severe drought and excessive moisture is expected to increase. Wheaton et al. (2013) show the probability for both these events spatially and temporally is expected to increase in the future. The Intergovernmental on Climate Change (IPCC 2007) estimate the frequency of extreme precipitation events will increase with a 90 to 99% certainty rating. Also, the area affected by drought will also likely increase (with a 66% probability of occurrence).

This document is one of a series that is examining the risks of potash mining companies related to extreme climate events (Wheaton et al. 2013, Wittrock 2013 draft, Wheaton 2013 draft and Pittman et al. 2013 draft). The potash mining industry is relatively new to the Qu’Appelle River Watershed. The majority of the mines becoming operational in the late 1960s and early 1970s, and therefore earlier multi-year extreme drought (e.g., 1930s) and excessive moisture (e.g., 1950s) events did not affect the industry. Recent years of drought (1999-2003) and excessive moisture (2010-2013) may have impacted the mines operations.

SRC Publication No. 13462-5E13 1 Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed

Figure 2 Major Natural Catastrophes in Canada and USA in 2012 (adapted from Munich RE 2013) Climatic trends on the Canadian Prairies and portions thereof have been analyzed by various researchers (e.g., Bonsal et al. 2001, Bonsal and Regier 2007, Wheaton et al. 2008, Sauchyn 2010, and Bonsal et al. 2011). These studies were all large scale in nature, either Canada wide or the agricultural portion of the Canadian prairies. Many of the studies focused on drought. For example, several extreme years were found including the 1930s, 1961, 1988 and the 2001-2002 droughts. More recently some analyses have also included recent excessive moisture events, especially extreme weather events (e.g., Hopkinson 2010, Hopkinson 2011, and US Army Corps of Engineers 2012). Wittrock (2012) examined the Upper Qu’Appelle River Watershed and the Moose Jaw River Watershed for drought and excessive moisture conditions and compared these conditions to crop yields.

The documents listed in the previous paragraph assist with knowing what large scale systems occurred or when and where extreme precipitation events may have taken place. This study area for this project is the Qu’Appelle River Watershed. It is located in the southeastern portion of Saskatchewan. Portions of the watershed (Moose Jaw River and the southwestern edges of the Upper Qu’Appelle and Wascana Creek watersheds) are located in the Palliser Triangle (Figure 3). This region’s climate can vary from severe droughts as experienced in the 1980s and 2000s to excessive moisture as has occurred in 2010-2012.

2 SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013

Figure 3 Palliser Triangle in the Canadian Prairies (Lemmen and Dale-Burnett 1999) Purpose and Objectives The purpose of this report is to examine the climate of the Qu’Appelle River Watershed over the last 110 years. This information will assist in improving the planning and preparation for future extreme drought and excessive moisture events. The objectives are to:  Develop temperature and precipitation databases based on monthly values for the study area and surrounding region o Conduct trend analysis on the dataset  Develop databases for study area and surrounding region using various climatic indices including the Palmer Drought Severity Index, the Standardized Precipitation Index and the Standardized Precipitation and Evapotranspiration Index. o Characterize monthly, seasonal and multi-year events in terms of intensity, duration, frequency and spatial pattern.  Document the methods and results. Data and Methods The monthly temperature and precipitation datasets were obtained from Environment Canada (Vincent et al. 2012 and Mekis and Vincent 2011). The temperature dataset is a homogenized dataset that corrects for non-climatic shifts such as station relocation and changes in observing practices and automation (Vincent et al. 2012). The adjusted precipitation dataset corrects for wind undercatch, evaporation and gauge specific wetting losses (Mekis and Vincent 2011). The stations available in the watershed and surrounding area are: Davidson, Indian Head, Kelliher, Moose Jaw, Moosomin, Outlook, Paswegin, Regina, Yellow Grass and Yorkton. The data period and completeness varies from location to location with Indian Head, Moose Jaw and Regina being the most complete for temperature. Indian Head and Regina are the most complete for precipitation. However, precipitation readings ended in 2006 at all of the stations except Kelliher, Yellow Grass and Yorkton. This results in an analysis gap of the recent years of excessive moisture. Seasonal, that is, winter (December, January February), spring (March, April, May), summer (June, July, August) and autumn (September, October, November)) as well as yearly trends are examined. Trends or regression analysis using Pearson Product moment

SRC Publication No. 13462-5E13 3 Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed analysis with an output of the coefficient of determination (R2) was carried out using Microsoft Excel (2010).

Measured climate station data is not uniform in space or time and thus creates potential analysis gaps. Therefore, gridded datasets are beneficial when examining watersheds especially watersheds that have a limited number of long term climate stations. This report analyzes characteristics of three indices: the Palmer Drought Severity Index (PDSI), the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI). These indices incorporate various climate parameters giving magnitudes of drought and excessive moisture. Each of the indices utilizes slightly different parameters therefore give slightly different results. The indices are further in more detail below.

Several gridded datasets are available, so it is necessary to choose the one(s) that best fit the needs of the analyses. Meinert et al. (2010) compared observed station data with three gridded datasets (ANUSPLIN, CANGRID and Climate Research Unit Time Series 2.1 (CRU)) for the Canadian Drought Research Initiative (DRI) Project. They found the ANUSPLIN dataset was the most comparable to observed station data, provided the best spatial coverage and capture of the extremes. This dataset is on an approximate 10 km grid resolution covering the period of 1901- 2005. The dataset contains monthly total precipitation and average maximum and minimum monthly temperatures generated using thin-plate smoothing splines (Hutchison 2004, McKenney et al. 2006). The monthly PDSI and SPI were calculated for each grid by Meinert et al. (2010).

Developed by Palmer (1965), the PDSI is a meteorological drought index utilized to evaluate periods of wet and dry conditions. The index is useful for longer-term (seasonal to annual) applications particularly for agriculture and surficial hydrology (Bonsal and Regier 2007, Guttman 1998). The calculation of PDSI requires precipitation information from the current month and from previous months (Guttman 1998) thus giving a long-term memory of previous moisture conditions. The data series are analyzed to determine the amount of moisture required for normal climate during each month. PDSI values typically range in value from +4 to -4 (Guttman 1998, Bonsal et al. 2011) and values outside those ranges are considered exceptional.

The Standardized Precipitation Index (SPI), developed by McKee et al. (1993) is used to monitor moisture supply conditions and interprets observed precipitation as a standardized departure of the precipitation probability distribution function. The purpose of SPI is to have a single value so that regions can have precipitation levels compared with each other (Meinert et al. 2010, Bonsal et al. 2011). Guttman (1998) found the 12-month SPI had a strong correlation with PDSI values.

The SPEI was calculated by Bonsal (p.comm. 2013) using the CANGRD dataset for usage in the Vulnerability and Adaptation to Climate Extremes in the Americas (VACEA) project. Bonsal found close comparison between ANUSPLIN and CANGRD datasets when analysing the SPEI dataset. The CANGRD dataset is a gridded monthly precipitation and temperature dataset covering the 1900-2011 period and has a spatial resolution of 50 x 50 km (Zhang et al. 2000). CANGRD temperature and precipitation and a normalization of a water balance using the methods of Vincente-Serrano et al. (2010) were used to calculate SPEI. The SPEI is a relatively new index and should be useful for hydrologic analyses because the index incorporates both precipitation and temperature. Wittrock et al. (draft 2013) developed categories for SPEI because

4 SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013 none were provided by Vincente-Serrano et al. (2010). Wittrock et al. (draft 2013) assumed the same categories would be relevant for SPEI as they are for SPI. Classifications for drought and excessive moisture for PDSI, SPI and SPEI are categorized in Table 1.

Table 1 PDSI, SPI, SPEI Classifications (Palmer 1965, McKee et al. 1993, Wittrock et al. draft 2013)

Classification PDSI SPI SPEI Drought Exceptional ≤ -5 ≤ -2.5 ≤ -2.5 Extreme > -5.0 to -4.0 > -2.5 to -2.0 > -2.5 to -2.0 Severe > -4.0 to -3.0 >-2.0 to -1.5 >-2.0 to -1.5 Moderate > -3.0 to -2.0 > -1.5 to -1.0 > -1.5 to -1.0 Mild > -2.0 to -1.0 > -1.0 to -0.5 > -1.0 to -0.5 Near Normal > -1.0 to 1.0 > -0.5 to 0.5 > -0.5 to 0.5 Excessive Moisture Mild 1.0 to < 2.0 0.5 to < 1.0 0.5 to < 1.0 Moderate 2.0 to < 3.0 1.0 to < 1.5 1.0 to < 1.5 Severe 3.0 to < 4.0 1.5 to < 2.0 1.5 to < 2.0 Extreme 4.0 to < 5.0 2.0 to < 2.5 2.0 to < 2.5 Exceptional ≥ 5.0 ≥ 2.5 ≥ 2.5

Database development for the indices utilized in this report is similar to previous work (e.g., Wittrock 2012 and Wittrock et al. 2011). The PDSI, SPI and SPEI grid values were extracted from the databases for the entire Qu’Appelle River Watershed. This watershed is comprised of the following smaller watersheds: the Moose Jaw, Upper Qu’Appelle, Wascana Creek and Lower Qu’Appelle (Figure 4). Watershed boundaries were supplied by the Saskatchewan Water Security Agency (p.comm. 2010). The analysis used monthly and yearly data focusing on the September to August period, that is, the agricultural and hydrologic year. The ten most extreme drought and excessive moisture months and years were selected and ranked for the entire Qu’Appelle River watershed. The extreme value is a point value within the grids of the entire watershed. Temporal trends are plotted for each of the three indices for the period of record.

SRC Publication No. 13462-5E13 5 Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed

Figure 4 Approximate locations of climate stations and potash mines in and around the Qu’Appelle River Watershed (base map: Saskatchewan Watershed Authority 2009)

Spatial patterns were also examined. The data was imported into SURFER, a GIS package (Golden Software 2013) in order to map the climate indices. The Qu’Appelle River Watershed is evaluated based on the above listed indices; time period and spatial pattern to explore the characteristics and patterns of the excessive moisture and drought events.

Temperature and Precipitation Trends

This section examines the temperature and precipitation trends annually and seasonally using the homogenized temperature and adjusted precipitation dataset to determine trends that have occurred in the last 100 years. Six climate stations are examined: Regina, Yorkton, Indian Head, Moose Jaw, Moosomin and Outlook (Figure 3). These climate stations were chosen because of their most complete records as well as their extended recording period. However, the period of record varies with each station and the linear regressions and coefficient of determination (R2) are calculated for the station with the longest period of record for the two stations examined. The graphs for this section are located in Appendices A and B. The other locations were used, such as Kelliher, when point extremes were documented. Temperature Trends Annual and seasonal temperature trends indicate increasing or decreasing temperatures. Temperature trend analysis may assist with explaining the changes in level of evaporation, amount of moisture the atmosphere is able to hold without precipitating and the potential of changing precipitation types, e.g., rain in winter as opposed to snow due to warmer temperatures.

6 SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013

The temperature trends for the Qu’Appelle River Watershed and neighbouring areas are assessed. Table 2 portrays the 1971-2000 annual and seasonal averages as calculated from the homogenized dataset. Indian Head is generally the coolest location, except in winter. Yorkton has the coolest average winter temperatures at -15°C. Moose Jaw has the highest average temperatures for the 1971-2000 period.

Table 2 1971-2000 Annual Average Temperatures for Selected Climate Stations (red shading indicates warmest locations, blue shading indicates coolest locations).

1971-200 Average Davidson Indian Head Kelliher Moose Jaw Moosomin Outlook Paswegin Regina Yellow Grass Yorkton Annual Average 1.9 1.6 1.7 4.1 2.6 3.4 1.2 3.1 3.2 2.0 Max 8.1 7.6 7.4 10.2 8.1 9.2 6.9 9.1 9.8 7.5 Min -4.4 -5.0 -4.0 -2.1 -3.0 -2.4 -4.5 -2.9 -3.2 -3.6 Winter Average -14.8 -14.9 -14.8 -11.4 -14.1 -12.5 -16.1 -13.3 -13.0 -15.0 Max -9.5 -10.0 -9.8 -6.2 -9.4 -7.7 -10.9 -8.4 -7.5 -10.3 Min -20.0 -20.9 -19.7 -16.6 -18.8 -17.4 -21.1 -18.3 -18.4 -19.7 Spring Average 2.8 2.4 2.5 4.6 3.3 4.3 2.2 3.9 3.9 2.5 Max 9.0 8.5 8.3 11.0 9.1 10.3 8.0 10.0 10.6 8.3 Min -3.5 -4.3 -3.3 -1.8 -2.4 -1.7 -3.7 -2.2 -2.6 -3.3 Summer Average 16.9 16.1 16.5 18.3 17.5 17.6 16.4 17.9 18.0 16.9 Max 24.2 23.3 23.0 25.3 24.0 24.4 22.9 24.7 25.5 23.3 Min 9.6 9.1 9.9 11.2 11.0 10.9 9.9 11.0 10.5 10.5 Autumn Average 3.1 2.6 2.6 4.8 3.6 4.5 2.5 4.0 4.3 3.1 Max 9.1 8.4 8.0 10.9 8.8 10.0 7.9 10.0 10.7 8.4 Min -3.1 -3.8 -2.8 -1.4 -1.6 -1.3 -3.0 -2.1 -2.3 -2.2

Annual Temperature Trends Six climate stations, in or close to the Qu’Appelle River Watershed, (Regina, Yorkton, Indian Head, Moose Jaw, Moosomin and Outlook (Figure 3)) have similar increases in annual average temperature trends (Figure A-1). Indian Head has the longest period of record of the six climate stations examined. It has an increasing temperature trend with an R2 of 0.38 and the annual average temperature had increased by more than 2°C along the trend line for the period of record (1891-2012). The late 19th century and early 20th century were the coldest with increases in temperature in the 1960s, 1980s and late 1990s, early 21st century. The warmest years at all the sites were 1931, 1981 and 1987 where the sites were all at least 2.0°C above their 1971-2000 average value. The coldest values for all long-term climate station locations in the watershed occurred pre-1955. Indian Head had the coldest annual average temperature of -2.1°C in 1893. The warmest annual average temperature occurred at Moose Jaw in 1987 with a temperature of 6.9°C.

Annual minimum and maximum temperatures are also examined (Figures A-2 to A-3).The minimum annual temperatures have largest increasing trend with Indian Head having a R2 of 0.54 and the minimum annual temperatures increased by nearly 4°C over the period of record (Figure A-2). The maximum annual temperatures have also increased but not as dramatically with an R2 of 0.2 and just under 2°C temperature increase in the last 100 years at Indian Head (Figure A-3).

Seasonal Temperature Trends The seasonal variability of average, maximum and minimum temperatures further indicates the temperature increases of the last 100 years (Figures A-4 to A-15).

SRC Publication No. 13462-5E13 7 Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed

Winter The winter season (Figures A-4 to A-6) (December, January, February) has the highest temperature variability of the four seasons. The winter season average had the highest mean maximum temperature of -4.0°C at Moose Jaw in 1931. The average maximum temperature at Moose Jaw in 1931 was 3.5°C while the average minimum that year was only -9.2°C. The coldest winter in the region was at Kelliher in 1936 with an average mean low temperature of -22.9°C. That winter had an average maximum temperature of -17.9°C and an average minimum temperature of -27.8°C. Winters are highly variable temperature wise. The average winter temperatures, at six long-term climate stations, varied by 15°C between the coldest and warmest winters.

The temperature trends over the period of record indicate extreme year to year fluctuations when comparing the annual and seasonal temperatures to the 1971-2000 averaging period. Both the average monthly maximum and minimum winter temperatures have been increasing over the period of record but the minimum temperatures have been increasing the most. Indian Head data has an R2 value of 0.22 and the minimum winter temperatures increasing by nearly 6°C between 1892 and 2012. The R2 for the maximum winter temperature at Indian Head is lower at 0.13 but the line has a positive slope, indicating an overall increasing trend. The warmest winters, that is, those warmer than the 1971-2000 average have occurred in the last 25 years with 16 years above average at Indian Head. In comparison only two winters during 1892-1914 had average monthly temperatures above the 1971-2000 average.

Spring The spring season (Figure A-7 to A-9) (March, April, May) also indicates an increasing temperature trend over the last hundred years. At Indian Head, the temperature variability in spring is not as extreme as it is in the winter. Although the variability is not as pronounced; spring has the same number of years above the 1971-2000 average at Indian Head as there were in winter. The spring temperature continues to have a general increase in the last 100 years for all climate station locations. The extreme lows have continued to occur as witnessed in 2002, but they are not as frequent as in the first half of the period of record. The fourth coldest spring on record was 2002. The three previous extreme cold springs were in the late 19th and early 20th centuries.

The increasing spring average temperature is further illustrated between 1988 and 2012 when 16 of the years were above the 1971-200 average. The 1891-1915 period had only two years warmer than the 1971-2000 averaging period (1905 and 1910).

Summer Summer (Figures A-10 to A-12) (June, July, August) has the smallest year to year variability of the four seasons. Most of the climate stations again show increasing average monthly temperatures; particularly the minimums or overnight lows. The maximum, or daytime high temperatures are also generally increasing but with lesser magnitude. One exception is Outlook. The graph and regression line illustrates the minimum temperatures have been increasing over the station’s period of record but the maximum temperatures are decreasing.

As with the other seasons, recent years’ temperatures have been above normal. At Indian Head’s climate station 18 of the last 25 years (1988-2012) were above the 1971-2000 summer average

8 SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013 temperatures. The 1891 to 1915 period had only two years at or above the 1970-2000 average (1894 and 1900).

Autumn As with the other seasons, the autumn average temperatures have increased over the period of record (Figure A-13 to A-15). In addition, the variability is less pronounced in autumn than spring and winter but more than summer. As with the other seasons, the minimum temperatures regression line has a steeper upward trend than the maximum temperature trend line indicating that the night-time lows are increasing more than the day-time highs. Similar to the winter and spring seasons, the minimum temperatures in the earlier part of the record are much lower than in more recent times. .

As with the other seasons, recent years’ temperatures were more often above the 1971-2000 average than the early portion of record keeping. Indian Head’s average annual temperatures were at or above the average for 17 years during 1988-2012, while the 1891-1915 period had 19 years below average. Precipitation Trends Precipitation is extremely variable on a yearly, seasonal and daily basis. It can be highly localized or cover an extended region. Both the lack of it and too much of it can impact all factors of society including industry. Precipitation trends over the 1898 to 2012 period are plotted for six locations in and around the Qu’Appelle River Watershed. The period of record for the climate stations is variable with the longer and most data complete records for Regina and Indian Head. However, neither of these two stations have records for the 2007 to 2012 period. As a result, the most recent wet period are not being fully incorporated into the analysis. Figures B-1 to B-5 show the departures from the 1971-2000 average in percentage for period of record on a seasonal and yearly basis.

Annual Precipitation Trends The trends in precipitation vary with location (Figures 5 and B-1). For example, Regina has a positive trend line over its (1898- 2006) period of record and an R2 value of 0.02. Alternatively, Indian Head with its similar period of record (1900-2006) has negative regression trend line and an R2 of 0.02 as well.

Plots of the precipitation trend lines and the clusters of above and below average as well as determining if these clusters occur in all locations illustrates when potentially cumulative impacts of above or below normal precipitation occurred. Figure 5 includes data from all six long-term climate stations for their period of record. Plotting all the climate stations on one graph gives an indication of the regional pattern of the below or above average moisture events. There were five extended years with below normal precipitation: the early 20th century, the 1930s, the late 1950s and early 1960s, the 1980s and 2001-2003. There were three extended periods with above normal precipitation: the late 1940s to early 1950s, and the early 1970s. The most recent extended excessive moisture spell has limited data (e.g., Kelliher, Yellow Grass and Yorkton). Yellow Grass’s extreme excessive moisture year was in 2011 with more than 725 mm reported. Since the late 1980s, year to year precipitation variability between above and below average precipitation levels occurred between the climate stations For example 1991 had all station

SRC Publication No. 13462-5E13 9 Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed reporting at least 20% above average while 1992 all the stations reported below average precipitation. This yearly variability appears to have continued.

Figure 5 Annual Precipitation Departures from the 1971-2000 Average (light orange ovals indicate below average precipitation periods; light blue ovals indicate above average precipitation periods)

Seasonal Precipitation Trends Annual precipitation gives only partial information on below and above average precipitation occurrences. Examination of seasonal precipitation allows a more complete characterization of the timing of the events.

Winter Winter is normally the season of snowfall and the convenient way to “store” water. The amounts of precipitation also influence infrastructure construction, damage and maintenance. Both Regina and Indian Head data indicate a trend of increased precipitation in winter (Figure 6 and B-2). The early portion of the recording period in Regina (1899-1925) had below the 1971-2000 average winter precipitation. Indian Head had similar precipitation amounts, except for 1917-1919 when above normal precipitation was recorded.

When all six climate stations are compared (Figure 6) for winter precipitation, there are three extended and two shorter duration below average periods. In comparison, winter had above average precipitation in the late 1940s and early 1950s as well as the mid- to late 1960s and first half of the 1970s. From 1989 to present, there appears to be year-to-year winter fluctuation was greater in precipitation amounts among locations and time periods.

10 SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013

Figure 6 Winter Precipitation Departures from the 1971-2000 Average (light orange ovals indicate below average precipitation periods; light blue ovals indicate above average precipitation periods)

Spring

Spring precipitation levels in the Qu’Appelle River Watershed is highly variable ranging from more than 75% below normal to in excess of 150% above normal (Figures 7 and B-3). The number of consecutive springs having extreme events is increased in spring (Figure 7) with approximately 12 below average precipitation moisture and five above average precipitation events. However, these individual events usually last only two years. The 1930s, late 1940s, late 1950s and early 1960 had the longest consecutive springs with below average precipitation. The mid-1950s and 1970s had the highest number of consecutive springs with excessive moisture. Above average spring precipitation did occur in the area as documented by Hopkinson (2010 and 2011). He found the spring 2010 was the wettest spring since 1955 at 169% of normal. Hopkinson (2011) documented the southeastern portion of Saskatchewan in the Moosomin region had between precipitation amounts of 150 to 200% of average in the April 1 to July 4th, 2011 period.

SRC Publication No. 13462-5E13 11 Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed

Figure 7 Spring Precipitation Departures from the 1971-2000 Average (light orange ovals indicate below average precipitation periods; light blue ovals indicate above average precipitation periods)

Summer Summer precipitation levels are also highly variable with the regression line indicating no upward or downward trend (Figures 8 and B-4). This variability is further illustrated in Figure 8. There are very few years when all locations have consecutive summers with above or below normal precipitation. In general, the summers with consecutive above normal moisture amounts were 1906-1909, the early 1950s and the early 1990s. The below average precipitation summers were in the 1930s, late 1950s and early 1960s as well as the late 1960s. All six stations recorded below average moisture occurred in 1961 and 1967 and above precipitation was in 1942, 1954, and 1963.

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Figure 8 Summer Precipitation Departures from the 1971-2000 Average (light orange ovals indicate below average precipitation periods; light blue ovals indicate above average precipitation periods)

Autumn Autumn precipitation levels are also highly variable with no upwards or downwards trend in the regression line (Figures 9 and B-5). At Indian Head, precipitation can range from an extreme low of 18.6 mm in in 1976 to an extreme high in 1959 of 220.5 mm. A few consecutive autumns had above and below average levels. The 1920s, mid 1940s and mid 1980s had back to back autumns with above average precipitation. The 1930s, late 1940s, early 1960s, late 1980s and early 21st century had autumns with back to back below average precipitation (Figure 9).

Figure 9 Autumn Precipitation Departures from the 1971-2000 Average (light orange ovals indicate below average precipitation periods; light blue ovals indicate above average precipitation periods)

SRC Publication No. 13462-5E13 13 Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed

Climate Indices As discussed in the methods section, measured climate station data is not uniform in time and space therefore to help assess variability gridded data may be more useful. This section examines three gridded datasets: the Palmer Drought Severity Index (PDSI), the Standardized Precipitation and Evapotranspiration Index (SPEI) and the Standardized Precipitation Index (SPI) both temporally and spatially (Appendix C).

As discussed in the methods section, the indices are calculated differently and thus give somewhat different results and information. The indices also have different grid sizes with PDSI and SPI having an approximate 10km grid resolution while the SPEI has an approximate 50 km x 50 km grid resolution. The ten most extreme drought and excessive moisture years for each of the three indices show extreme drought conditions are similar across the indices while excessive moisture years do not have as many common years (Table 3). The commonality of the drought years could be an indication that extreme droughts cover larger areas and affect both the hydrologic and climatologic regimes where as excessive moisture years tend not to affect all of the indices the same way in part due to the different variables used in their calculations. For example, SPI does not include temperature and evaporation whereas PDSI and SPEI does.

The most extreme drought of 1961 was common across all three indices while the most extreme excessive moisture year was 1954 for both SPI and PDSI while SPEI’s extreme excessive moisture year was 1999. The three indices had six out of the 10 years in common while only two of the excessive moisture years were the same. This disparity in excessive moisture years may be due to the different time frames of the indices. SPI and PDSI data ends in 2005 with SPEI extending to 2011 resulting in SPEI three excessive moisture years occurring in 2007, 2010 and 2011.

Table 3 Maximum and Minimum Values of PDSI, SPEI and SPI in the Qu’Appelle River Watershed

Maximum Values - Excessive Moisture Conditions Minimum Values - Drought Conditions Rank SPEI SPI PDSI Rank SPEI SPI PDSI 1 1999 2.9 1954 2.8 1954 9.9 1 1961 -2.7 1961 -4.5 1961 -8.5 2 1953 2.6 1907 2.4 1907 8.2 2 1988 -2.4 1929 -3.2 1958 -6.8 3 1927 2.6 1953 2.2 1909 7.0 3 1949 -2.1 1958 -3.1 1959 -6.8 4 2011 2.5 1999 2.1 1955 6.8 4 2001 -2.1 1937 -2.6 1988 -6.7 5 1954 2.5 1974 2.1 1991 6.6 5 1937 -2.0 1988 -2.6 1984 -6.2 6 2010 2.5 1923 2.1 1951 5.9 6 1936 -2.0 1967 -2.4 1937 -5.9 7 1907 2.3 1942 2.0 1902 5.8 7 1929 -2.0 2001 -2.4 1981 -5.5 8 2007 2.1 1991 2.0 1927 5.8 8 1958 -1.9 1924 -2.3 1931 -5.5 9 1916 2.0 1993 2.0 1966 5.4 9 1984 -1.9 1914 -2.2 1930 -5.4 10 2004 1.9 1951 2.0 1974 5.4 10 1919 -1.8 1984 -2.1 1929 -5.2 Commonalities in extreme years: Yellow (SPEI, SPI and PDSI); Blue (SPEI and SPI); Green (SPEI and PDSI); and Pink (SPI and PDSI). Palmer Drought Severity Index

Temporal Patterns Figure 10 contains the temporal pattern of PDSI for three locations in the Qu’Appelle River Watershed. PDSI is calculated in a grid format therefore the grid squares located close to Belle Plaine, Esterhazy and mines were chosen for analysis. The drought and excessive moisture patterns are relatively similar over the period of record (1901-2005) with a few

14 SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013 exceptions. In the early portion of the 20th century, the Qu’Appelle River Watershed at these locations was moderate to severely moist to exceptionally moist in the Belle Plaine region in 1907 and 1909 with values in excess of 6 (exceptionally moist). This was followed by nearly 20 years with PDSI fluctuating between severe drought to moderate wet (refer to Table 1 for categories).

The continuous drought event of the 1930s begins in the 1929 PDSI values (severe drought) and with the exception of 1935, the negative PDSI values continued until 1942 when the values rose to 4 (extreme excessive moisture) or greater. From 1943 to 1956, moisture levels in the three grid cells increased to high PDSI values at all sites (1954-1956) above the extreme moisture range with Belle Plaine region reaching the exceptional moisture level (> than 6). The next six years progressed from near neutral or normal conditions (1957) to beyond exceptional drought in 1961 with values in the Esterhazy region nearly the -8 level, well below the category of exceptional drought.

The next 15 years fluctuated between moderate excessive moisture to mild drought until 1977. The years from 1977 to 1989, the majority of grid cells had moderate to exceptional drought. The eastern portion of the watershed had near normal to mild excessive moisture in 1985 and 1986. From 1990 to 2005, the two eastern grid cells had near normal to severe excessive moisture PDSI values. The grid cell close to Belle Plaine also followed that trend with the exceptions of 1998 and 2001 when PDSI values were in the moderate drought range.

Figure 10 Palmer Drought Severity Index (1901-2005)

Spatial Patterns The ten most extreme PDSI years are listed in Table 3 and plotted in Figures C-1 and C-2. These maps show the variability of PDSI throughout the watershed where one location may be categorized as having exceptional excessive moisture conditions while another portion of the watershed may have near neutral conditions during the same period.

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Drought The spatial patterns (Figure C-1) of the September to August drought events illustrate that while one portion of the basin can suffer extreme drought the other areas might be near neutral. For example, 1930 was the ninth most extreme PDSI year. The northwestern portion had PDSI values in the -5 to -6 range (exceptional drought) while the southeastern edge was neutral (-1 to 1). The most extreme droughts affected the eastern side of the watershed for six years of the 10 most extreme years including 1931, 1937, 1958, 1961, and 1984. The western portion of the watershed had four years of the most extreme drought. However, for nine of the 10 most extreme drought years the entire watershed had PDSI values that were classified as “drought conditions”.

The sequence and continual extreme droughts spatially would likely result in cumulative impacts. Two specific time periods had consecutive low PDSI values: 1929, 1930, and 1931 and the second was 1958, 1959, 1961. As illustrated in the temporal graph of yearly PDSI values (Figure 10), the drought conditions continued in the 1930s, although they were not as extreme as the early years.

Excessive Moisture Excessive moisture spatial patterns (Figure C-2) also illustrate variability throughout the watershed. For example, 1965-1966 had near normal conditions in the central portion of the watershed but in the watersheds’ northern reaches, PDSI values of 5 to 6 were attained indicating exceptional excessive moisture conditions in that region.

The most extreme excessive moisture year for the watershed was 1953-1954 when the majority of the watershed had PDSI values of 5 or higher. Five of the top ten years had portions of the watershed with PDSI values greater than 6 (1907, 1909, 1954, 1955, and 1991). Standardized Precipitation Evapotranspiration Index

Temporal Patterns As stated in the methods section SPEI is calculated on a grid format with two grid cells chosen for comparison. The first is located north of Regina ( region) and the second is east of Esterhazy, close to the Manitoba border (Figure 11). SPEI does not include pre-existing conditions like PDSI therefore larger year to year fluctuations occur. The SPEI temporal trends were similar to the PDSI, with a few exceptions. The start of the 20st century indicated mild to moderate excessive moisture but only until 1907. The years 1909 and 1911 show the differences between the western grid point (SPEI value of >1.5 or severe excessive moisture) while the eastern grid point had near normal conditions.

The 1930s had moderate to extreme drought with the exception of 1935 with SPEI values in the 1.5 range, i.e., moderate excessive moisture. The lowest SPEI value occurred in 1961 when both locations were below the -2 or extreme drought range. The highest SPEI values were in 1954 and 1999 (Regina Beach location) with values greater than 2. The highest SPEI values were in the eastern side of the Qu’Appelle River Watershed (east of Esterhazy) in 1999 and1927 with values ranging between 1.5 and 2 (severe excessive moisture). The SPEI dataset is the only one of the three dataset that extends to 2011 thus allowing for analysis of the most recent high precipitation events. The 2008-2011period had multiple years with SPEI values greater than one in both grid cells. The last time this number of excessive moisture years occurred was in the 1950s.

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Figure 11 Standardized Precipitation Evapotranspiration Index (1901-2011)

Spatial Patterns

Drought SPEI spatial distribution of the ten most extreme drought years (Figure C-3) shows a generally more cohesive pattern than PDSI. A larger portion of the watershed falls within one drought category and the entire Qu’Appelle River Watershed is categorized as being in a drought event throughout the basin ranging from mild to exceptional drought conditions. The exceptional drought category for SPEI occurred only once in 1961.

The sequential year pattern of extreme droughts that was noted in PDSI was not as pronounced with SPEI values.

Excessive Moisture Excessive moisture patterns of SPEI (Figure C-4) are less coherent across the watershed as compared with the drought patterns. For example, in 2007, mild drought was being observed in the south central portion of the Qu’Appelle River Watershed while the watershed’s northern reaches had SPEI values of 2 to 2.5 (extreme excessive moisture).

Exceptional excessive moisture years (SPEI values greater than 2.5) occurred six times in the 10 most extreme years including 1927, 1953, 1954, 1999, 1910 and 1911. The location of this high value varied from year to year. The only year when three grid cells shared that exceptional value was 1999, when the western portion of the watershed was classified having extreme or higher excessive moisture conditions.

The four most recent high SPEI values show that the northern portion of the watershed had the highest SPEI values in 2007 and 2010. The southwestern portion had SPEI values rated at severe

SRC Publication No. 13462-5E13 17 Characterization of Historic Drought and Excessive Moisture September 2013 in the Qu’Appelle River Watershed excessive moisture in 2004, while the southern portion had values of extreme or exceptional in 2011. Standardized Precipitation Index

Temporal Patterns Only precipitation is used to calculate SPI resulting in slightly different patterns than the SPEI or PDSI graphs (Figure 12). The extreme years are similar in intensity, especially the drought years (1961 and 1929). The excessive moisture years are a little different in their intensity. SPI extreme excessive moisture year of 1942 occurred on the eastern side of the watershed while the western side excessive moisture year was 1974.

Figure 12 Standardized Precipitation Index (1902-2005)

Spatial Patterns

Drought The spatial variability of droughts is apparent when using the SPI (Figure C-5). The northern portion of the watershed had the lowest SPI values in 1914, 1924 and 2001. The western portion had the lowest SPI values in 1929 and 1988, while the eastern portion was the lowest in 1958, and 1961. The most extreme drought year using SPI, as with PDSI and SPEI, was 1961 with values in the -4 to -4.5 range and covered approximately the eastern quarter of the watershed.

Similar to SPEI, there were no sequential extreme SPI drought years.

Excessive Moisture The variability of the SPI extreme excessive moisture years (Figure C-6) always have one portion of the watershed in near neutral conditions while another is in severe to exceptional excessive moisture levels. The most extreme excessive moisture year was 1954 when the

18 SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013 watershed’s northern quarter had SPI values of 2.5 or greater (exceptional excessive moisture). This was the second year of high SPI value for portions of the Qu’Appelle River Watershed, especially the eastern portion with values of 1.5 (severe) or higher.

Conclusions and Recommendations The potash mining industry in the Qu’Appelle River Watershed is relatively new with most of the mines beginning production in the late 1960s and early 1970s. Therefore, utilizing the information provided will assist the industry with their risk management strategies. Determining the climatic trends of the past assists with adaptive risk management strategies of many sectors including the mining sector. This report illustrates the extreme drought and excessive moisture events in the Qu’Appelle River Watershed in the last 110 years.

Several climatic trends are important to know and to use for risk management. Some highlights discovered from the temperature and precipitation trends section:  The late 19th and early 20th century had in general the coldest average annual temperatures;  The average annual temperatures have an upward trend but annual variability is still common;  The minimum annual average temperature has the greatest increase;  Winter temperatures are highly variable bot of the four seasons have increased the most;  Summer minimum temperatures have increased while summer maximum temperatures have stayed relatively constant;  Five periods had multiple years with below normal precipitation: early 20th century, the 1930s, the late 1950s and early 1960s, the 1980s and 2001-2003.  Three periods had above normal annual precipitation: the late 1940s to early 1950s, the 1970s and the most recent period from 2010 to 2013.  MAJOR GAP – lack of measured precipitation data from 2007 to present.

The three climatic indices also illustrate some interesting patterns.  The top 10 minimum extreme values (drought) had more similar years than the top 10 maximum extreme values (excessive moisture). This give an indication that extreme droughts are more widespread and are influenced by both temperature and precipitation while excessive moisture conditions may just be precipitation influenced.  The PDSI September to August temporal trend for the 1901-2005 period shows that the 1930s were in drought conditions while the late 1940s and early 1950s were excessive moisture. Low PDSI values returned in the late a 1970s and much of the 1980s with moderately high PDSI values returned in the 1990s.  The lowest PDSI values affected the eastern side of the watershed for six out of the 10 most extreme years: 1931, 1937, 1958, 1961 and 1984.  Five of the 10 years had portions of the watershed with PDSI values greater than 6: 1907, 1909, 1954, 1955 and 1991.  The SPEI September to August temporal trend for the 1901-2011 period is more variable than PDSI. It does however have the same general trend but more year to year and grid point variability. The recent years of 2009-2011 had positive SPEI values.

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 The SPI September to August temporal trend (1901-2005) is also highly variable like SPEI with similar years in negative values (e.g., 1930s, 1980s) or positive SPI values including the 1950s and 1990s.

The changing climatic conditions have an impact on hydrologic and societal conditions. For example, climatological droughts lead to hydrological droughts which can influence how society and industry work, especially if the drought lasts for an extended time period. Higher temperatures may influence the amount and timing of energy required for a plant to operate.

This report focused on temperature and precipitation as well as three climatic indices. It is recommended that additional climatological variables be examined as these may also influence potash mining operations in the Qu’Appelle River Watershed. For example, snow cover season variability and seasonality analysis should also be undertaken as it has implications on timing of spring run-off, infrastructure maintenance.

A current and future gap is going to be the lack of climate data. Many stations stopped reporting in 2007 and others stopped recording precipitation amounts that same year resulting in large data gaps.

Acknowledgements This work was funded by the Water Security Agency of Saskatchewan. Several people with WSA, fellow researchers (Elaine Wheaton and Jeremy Pittman) and the advisory committee for the “Risks to Mining Companies related to Extreme Climate Events” NRCan project provided invaluable advice and feedback. Thanks also go to Marlene Heskin and Val Ziegler for word processing carried out on this document.

20 SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013

References

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Mekis, É. and L.A. Vincent. 2011. An Overview of the Second Generation Adjusted Daily Precipitation Dataset for Trend Analysis in Canada. Atmosphere-Ocean 49(2):163-177. Doi: 10.1080/07055900.2011.583910

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Appendix A Temperature Trends

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Figure A-1 Annual Average Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook). Data Source: Vincent et al. (2012)

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Figure A-2 Minimum Annual Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

26 SRC Publication No. 13462-5E13 Characterization of Historic Drought and Excessive Moisture in the Qu’Appelle River Watershed September 2013

Figure A-3 Maximum Annual Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-4 Winter Average Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-5 Winter Minimum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-6 Winter Maximum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-7 Spring Average Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-8 Spring Minimum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-9 Spring Maximum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-10 Summer Average Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-11 Summer Minimum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-12 Summer Maximum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-13 Autumn Average Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-14 Autumn Minimum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Figure A-15 Autumn Maximum Temperature Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Vincent et al. (2012)

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Appendix B Precipitation Trends

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Figure B-1 Annual Precipitation Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Mekis and Vincent 2011

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Figure B-2 Winter Precipitation Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Mekis and Vincent 2011

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Figure B-3 Spring Precipitation Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Mekis and Vincent 2011

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Figure B-4 Summer Precipitation Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Mekis and Vincent 2011

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Figure B-5 Autumn Precipitation Departures from the 1971-2000 Average (Regina & Yorkton, Indian Head & Moose Jaw, Moosomin & Outlook) Data Source: Mekis and Vincent 2011

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Appendix C Climate Indices – Spatial Analysis of Qu’Appelle River Watershed

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Figure C-1 Palmer Drought Severity Index - 10 extreme years of moisture deficit conditions

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Figure C-2 Palmer Drought Severity Index - 10 extreme years of moisture surplus conditions

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Figure C-3 Standardized Precipitation Evapotranspiration Index - 10 extreme years of moisture deficit conditions

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Figure C-4 Standardized Precipitation Evapotranspiration Index - 10 extreme years of moisture surplus conditions

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Figure C-5 Standardized Precipitation Index- 10 extreme years of moisture deficit conditions

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Figure C-6 Standardized Precipitation Index - 10 extreme years of moisture surplus conditions

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