TANBREEZ PROJECT CLIMATE AND HYDROLOGY AUGUST 2013 TANBREZ MINING GREENLAND A/S

Transcription

1 TANBREZ MINING GREENLAND A/S TANBREEZ PROJECT CLIMATE AND HYDROLOGY AUGUST 2013 Orbicon A/S Ringstedvej 20 DK 4000 Roskilde Denmark Phone Version Draft 1.2 Date 6. August 2013 Prepared OSMI

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3 TANBREZ MINING GREENLAND A/S TANBREEZ PROJECT ENVIRONMENTAL IMPACT ASSESSMENT August 2013 Orbicon A/S Ringstedvej 20 DK 4000 Roskilde Denmark Phone /32

4 TABLE OF CONTENTS 1 INTRODUCTION Kilavaat Anlinnguat area CLIMATIC CONDITIONS IN THE REGION INTRODUCTION Precipitation Wind pattern Fog Weather data collected at Killavaat Alannguat CATCHMENT AREAS at KILLAVAAT ALANNGUAT THE HYDROMETRIC STATION AT FOSTERSØ Discharge in Long term discharge OVERALL WATER BALANCE Conclusion of hydrological calculations REFERENCES...24 ANNEX 1 DISCHARGE DATA FROM FOSTERSØ...25 ANNEX 2 MEASURED AIR TEMPERATURE AT KILLAVAAT ALIANNGUT...27 ANNEX 3 MEASURED WIND SPEED AT KILLAVAAT ALIANNGUAT...28 ANNEX 4 MEASURED RELATIVE HUMIDITY AT KILLAVAAT ALIANNGUAT...29 ANNEX 5 MEASURED PRECIPITATION AT KILLAVAAT ALIANNGUAT...30 accumulated daily total...30 ANNEX 6 MEASURED WIND DIRECTION DATA AT Killavaat Aliannguat...31 hourly average values...31 ANNEX 7 MEASURED WIND CLASS FREQUENCY AT KILLAVAAT ALIANNGUAT /32

5 List of figures Figure 2-1 The location of the TANBREEZ Project in South Greenland Figure 3-1 Windroses from Qaqortoq and Narsarsuaq... 9 Figure 4-1 The weather station at Killavaat Alannguat...11 Figure 4-2 Monthly precipitation recorded at Killavaat Alannguat (St Mine Site) and in Qaqortoq Figure 4-3 Measured temperature at Killavaat Alannguat (St Mine Site) and in Qaqortoq Figure 5-1 Streams, rivers (blue lines) and lakes and their catchment areas (red lines) at Killavaat Alannguat. Fostersø (Foster Lake) is marked with 470 in the figure (the altitude of the lake) Figure 6-1 Hydrometric station at Fostersø Figure 6-2 Rating curve for Fostersø (see text for explanation) Figure 6-3 Measured water level in Fostersø (top), calculated outflow from Fostersø (middle) and measured air temperature (bottom) June October Figure 6-4 Correlation between the measured annual discharge from Lake Taseq in and the recorded precipitation in Qaqortoq during the same period Figure 7-1 Catchment areas and locations for discharge measurements(red figures)...22 List of Tables Table 4-1 Summary of climate data from Killavaat Alannguat measured between May and October Table 6-1 Estimated annual average, minimum and maximum discharge of Fostersø...20 Table 6-2 Measured annual discharge from Fostersø in - and estimated long-term annual discharge Table 7-1 Characteristics of key water courses in the project area /32

6 1 INTRODUCTION TANBREEZ Mining Greenland A/S is currently exploring the potential of mining Zirconia, Rare Earth Elements, Yttrium, Niobium, Hafnium and Tantalum mine (the TANBREEZ Project) at Killavaat Alannguat (Kringlerne) in South Greenland. The TANBREEZ Project includes two mine sites; one at the Killavaat Alannguat plateau at m altitude and another at the shore of Kangerluarsuk Fjord where all other mine facilities will be located. Fostersø, which is also situated at Killavaat Alannguat, has been identified as a possible location for deposition of tailings and waste rock. Fostersø is connected to Kangerluarsuk Fjord through the stream Laksetværelv which discharge into Lakseelv approximately 1 km from outlet in the fjord. In order to better characterise the actual climate at the mine site a weather station has been operated by Orbicon since May. This note present the climate data collected between May and October. To get a better understanding of the hydrology of the Killavaat Alannguat, and in particular the flow in streams and rivers that connect Fostersø with the fjord, Orbicon has been operating a hydrometric station that measure the out flow of water from Fostersø. This station has also been running since May and the data compiled so far is presented in this note. 6/32

7 2 KILAVAAT ANLINNGUAT AREA Kilavaat Anginnguat is situated in South Greenland at N, W (Figure 2.1) 20 km NE of the town Qaqortoq, 40 km SW of the airport and community Narssarsuaq and 10 km SE of the town Narsaq Narsarsuaq Narsaq TANBREEZ Qaqortoq Figure 2-1 Location of the TANBREEZ Project in South Greenland /32

8 3 CLIMATIC CONDITIONS IN THE REGION 3.1 INTRODUCTION South Greenland is situated at latitude North and is characterized by having arctic climate as the warmest month in the year has average temperatures below Celsius. At a regional scale the weather in South Greenland is mainly influenced by the North American continent and the North Atlantic Ocean. But the local climate is also heavily influenced by the Greenland Inland Ice. Another key factor is the all year round low sea surface temperature which is causing the South Greenland waters and coasts to be part of the arctic zone with summer temperatures below 10 degree C. The annual average air temperature at Qaqortoq is C (Source DMI: standard period ) some 20 km southwest of Killavaat Alannguat. Qaqortoq is situated close to the open coast and is under influence by an oceanic weather type with cool summers and relatively mild summers. The average January temperature in Qaqortoq is 5.5 degree C, while the average temperature in the warmest months (July and August) is 7.2 degree C (DMI 2012). Further inland, the weather type is more of a continental type and in South Greenland average summer temperatures can locally exceed the 10 degree threshold, which limit the arctic region. For example is the annual average air temperature at Narsarsuaq, 35 km northeast of Killavaat Alannguat C, the average January temperature is 6.8 degree C, but 10.3 degree C in July (DMI 2012). 3.2 Precipitation The annual average precipitation is measured to 615 mm at Narsarsuaq and 858 mm at Qaqortoq. This reflects the fact that the Narsarsuaq is dominated by continental and dry climate compared to the more humid air from the ocean at Qaqortoq. The highest monthly precipitation was measured to 374 mm in July 1966 in Qaqortoq. Local variations will occur as a consequence of changing topography affecting more rain in the high altitudes due to the orographic effect when humid air is forced up the mountain sides. In the winter period where precipitation is falling as snow, the snow depth is typically highest in February where the normal is 20 cm in Narsarsuaq and 41 cm in Qaqortoq. The absolute maximum snow depth in Narsarsuaq was measured to 103 cm in 1973 and in Qaqortoq 204 cm measured in /32

9 3.3 Wind pattern Gale force winds (above 13.8 m/s) are common in South Greenland in particular in winter. Furthermore, down directed offshore winds may reach sea level as outbursts of dry and relatively warm air (a foehn wind). This is a warm dry wind arising through adiabatic compression of the air sweeping down from the inland ice cap. Its relative humidity drops to 30-40% and the temperatures rises up to degrees C within an hour and remains very high for up to a day or two. The effect of the foehn wind is particularly marked in winter, when it results in rapid melting of the snow. The wind pattern in the region is much dependent of local variations in topography, even though the general atmosferic circulation is the driving force and determine whether the wind is coming from the costal region or perhaps from the caractheristic Föhn situations with strong gales coming from the NE. Both at Qaqortoq and Narsarsuaq is the prevailing wind direction NE or the opposite direction SW. Figure 3-1. Characteristic is that Qaqortoq is exposed for a much more differing wind pattern than Narsarsuaq who is very dominated by the orientation of the Narsarsuaq Valley Wind of character of storm or higher is mostly occuring from NE and is often of character of katabatic winds like the dry and warm Föhn winds. DMI station Qaqortoq DMI station Narsarsuaq Figure 3-1 Windroses from Qaqortoq and Narsarsuaq 9/32

10 On average the wind is less than 1.5 m/s or zero in 44% of the year at Narsarsuaq, compared to 41% at Qaqortoq. The frequency of storms counted as number of days a year with winds higher than 28.5 m/s, is 1.3 at Narsarsuaq and 2.7 at Qaqortoq. 3.4 Fog Even though the weather often is clear with excellent visibility, there are also periods with fog. The sea fog season is from May to September where relatively cold sea water is cooling the passing air masses with condensation and advection fog as a result. The sea fog is more frequent in Qaqortoq and decreasing when moving towards East, more inland and closer to the ice sheet. Number of days with fog and visibility less than 1 km is 18 days in Narsarsuaq and 53 days a year in Qaqortoq. 10/32

11 4 WEATHER DATA COLLECTED AT KILLAVAAT ALANNGUAT The weather station at Killavaat Alannguat since 23 May (Figure 4.1) has collected information on wind speed and direction, temperature, barometric pressure humidity and precipitation. The collected data are shown in Annex 2 7. A summary of the collected data are presented in Table 4-1. Figure 4-1 The weather station at Killavaat Alannguat 11/32

12 Air Temperature Humidity Wind speed Precipitation Meas. Seqence 1. hour 1. Hour 1. Hour avg 1 hour max 10. min avg Period value Avg Min Max Avg Avg Max Max Total Year/Month C o C o C o % m/s m/s m/s mm Table 4-1 Summary of climate data from Killavaat Alannguat measured between May and October The weather regime in the Killavaat Alannguat area takes an intermediate position between Qaqortoq and Narsarsuaq. This means that Killavaat Alannguat lies within the Arctic climate zone, with cool summers and cold winters. The annual precipitation from November to October at Killavaat Alannguat was 840 mm while only 660 mm was recorded in Qaqortoq during the same period. The monthly precipitation recorded at these two sites is shown in Figure 4-2. This higher 12/32

13 Air temperature (C 0 ) Precipitation (mm) precipitation measured at Killavaat Alannguat compared to Qaqortoq is most likely due to the fact that the station at Killavaat Alannguat is at 450 m altitude while the weather station at Qaqortoq is at 100m. A 5% increase in precipitation for every 100 altitude is often recorded in coastal Greenland St Mine Site Qaqortoq Figure 4-2 Monthly precipitation recorded at Killavaat Alannguat (St Mine Site) and in Qaqortoq St Mine Site Qaqortoq Figure 4-3 Measured temperature at Killavaat Alannguat (St Mine Site) and in Qaqortoq The temperature at Killavaat Alannguat during the summer months is almost similar to Qaqortoq, while in the winter months the temperature is much lower at Killavaat Alannguat (Figure 4-3). This is probably a combination of the more coastal climate at Qaqortoq and the 350 m difference in altitude. 13/32

14 Very high wind speeds have also been recorded at Killavaat Alannguat with a maximum wind speed of 52.4 m/s in September but many incidences with wind speed over 30 m/s (Annex 3). 14/32

15 5 CATCHMENT AREAS AT KILLAVAAT ALANNGUAT Streams, rivers and lakes at Killavaat Alannguat with their catchment areas are shown in Figure 5.1. The topography and morphology of this area varied considerably and include the steep and very significant 1200 meter high mountain ridge Redekammen, which forms the catchment boundary towards the South-east. Most of the area that surrounds Fostersø is an elevated plateau with almost no vegetation. This is in contrast to the lower and downstream Lakseelv-valley, which has dense vegetation of dwarf heat and grasses. Climate station Hydrology station Figure 5-1 Streams, rivers (blue lines) and lakes and their catchment areas (red lines) at Killavaat Alannguat. Fostersø (Foster Lake) is marked with 470 in the figure (the altitude of the lake) 15/32

16 The small stream Laksetværelv is the outlet of Fostersø. This stream has steep gradient resulting in a turbulent character with many small waterfalls. Laksetværelv joins Lakseelv about 1 km before the fjord. Lakseelv has a total catchment area of 26 km 2. Laksetværelv and its sub-catchment areas which cover 6.4 km 2 make up 25% of this area. The runoff pattern in the area varies according to the vegetation cover, soil layer thickness and topography. Typically an increase in water flow is recorded very shortly after precipitation events, even though Fostersø acts as a buffer and delays the flow to some extent. This is particularly obvious in the dry periods of the summer. A base flow or contribution from soil and ground water storage is usually not very important in cold region such as South Greenland. However, some base flow of soil and/or ground water must take place since water is flowing in Lakseelv throughout the year (that is even during mid-winter). Laksetværelv Laksetværelv Lakseelv with confluence from Laksetværelv Lakseelv and Valley upstream Laksetværelv 16/32

17 6 THE HYDROMETRIC STATION AT FOSTERSØ If Fostersø is to be used as tailings pond and for deposition of waste rock, it is important to known the retention time of water in the lake. To calculate this, a key figure is annual discharge but also annual variation, minimum flow and maximum flow is necessarily information. A hydrometric station has therefore been running at the outlet of Foster Lake since May (Figure 6.1). Figure 6-1 Hydrometric station at Fostersø This hydrometric station measures and store information about the water level in Fostersø. Based on the relation between the recorded water levels and a series of discrete discharge measurements it is possible to estimate the relation between these parameters and thereby calculate a continuous time series of discharge data. The hydrometric station has been operated with a Campbell Scientific data logger, measuring the water level through a submerged pressure transducer. The data logger is powered by a 12 volt accumulator and a 10 Watt solar panel. Data transmission is provided by the Iridium satellite system. 17/32

18 Water level m datum As a backup, a standalone submerged mini-data logger is deployed in the Fostersø approximately 50 meter north of the main station. Data from this station has not yet been collected. The rating curve expresses the relation between the water level in the lake (H) and the discharge (Q) and is dependent on the hydraulic conditions at the outlet from the lake. The rating curve for Fostersø is shown in Figure Flow m3/s Figure 6-2 Rating curve for Fostersø (see text for explanation) The rating curve makes it possible to construct a time series of discharge values derived from the continuously recorded water level in the lake. Figure 6.3 (top) show the measured water level in Fostersø between June and October. The middle figure shows the estimated outflow from the lake (through Laksetværelv) in the same period. The bottom figure show the measured air temperature during the same period as measured at the nearby climate station. 18/32

19 LTEMP [C] VNF [m3/s] VST [m Level] nov jan mar maj Privat DDH : 1003 Killavaat Aliannguat, Foster sø, outlet nov jan 2012 mar [ 1] [VST] [EDT] [Øje] [SS] 1003 [ 1] [VST] [VIR] [Øje] [MI] maj nov jan mar maj Privat DDH : 1003 Killavaat Aliannguat, Foster sø, outlet nov jan 2012 mar [ 1] [VNF] [EDT] [Mid] [DD] 1003 [ 1] [VNF] [VIR] [Øje] [MI] maj nov jan mar maj Privat DDH : 1004 Killavaat Aliannguat, Minesite 1004 [ 1] [LTEMP] [EDT] [Øje] [MI] nov jan 2012 mar 2012 maj Figure 6-3 Measured water level in Fostersø (top), calculated outflow from Fostersø (middle) and measured air temperature (bottom) June September 2012 It is clear from curve in Figure 6.3 (top) that the water level is changing with the rain events and snow melt. However, from mid-january to end of March the water level was steadily increasing in the lake. This is because the outflow was blocked by ice but a steady inflow of water still took place, probably mostly ground/soil water, leading to an increase in the level. When the first strong thaw/rain event occurs by the end of March the blockage melted and the water from the lake is forced out through Laksetværelv (Figure 6.3, top and middle). 6.1 Discharge in - The calculated discharge data (in Figure 6.3 middle) makes it possible to calculate the annual outflow from Fostersø during a full year (October -September ). This, 19/32

20 combined with data on precipitation in the region, makes it further possible to assess if the calculated data from -are typical, or perhaps reflects a particularly dry or wet year (see Section 6.2). St. No. Name Year Annual Average (m 3 /s) Annual Min (m 3 /s) Annual Max (m 3 /s) 1003 Foster Lake Oct -Sept * Table 6-1 Estimated annual average, minimum and maximum discharge of Fostersø * The calculated max. discharge at 0.6 m 3 /s originates from the melt of the ice blockage at the outlet in end March. The calculated ice free maximum discharge is 0.3 m 3 /s, measured the 8. June. 6.2 Long term discharge The discharge data in Section 6.1 is based on a single year s data. To assess if the calculated data from - are typical, or perhaps reflects a particularly dry or wet year, longer series of discharge series are required. One such data series exists from Lake Taseq close to Narsaq and some 12 km from Fostersø. Here data were collected from 1982 to These data were compared with precipitation data from Qaqortoq from the same period and a statistic significant correlation was found (Figure 6.4). It can further be calculated that that Taseq has a specific discharge of 42 m 3 /second/km 2 of catchment area. Assuming that the catchment areas of Taseq and Fostersø are comparable as they are both pure precipitation driven without any glacial ablation contribution, the main difference in their discharge is the size of the catchment area (Taseq is 7.4 km 2 while the catchment area of Fostersø is 3.4 km 2 ). 20/32

21 Annual average discharge st. 431 (l/s) y = x R² = Annual Precipitation Qaqortoq (mm) Figure 6-4 Correlation between the measured annual discharge from Lake Taseq in and the recorded precipitation in Qaqortoq during the same period Taking this into account, and using a specific discharge of 42 m 3 /second/km 2 of catchment area, the long term annual discharge from Fostersø can be calculated to 0.15 m 3 /s (Table 6-2). This value is considerably higher than the 0.08 m 3 /s measured in /. The difference is most likely due to the measuring period in - was unusually dry. Name Annual average in - (m 3 /s) Measured Model Average year Annual average long term discharge (m 3 /s) Max year Min. year Fostersø ,02 Table 6-2 Measured annual discharge from Fostersø in - and estimated long-term annual discharge. 21/32

22 7 OVERALL WATER BALANCE Based on the estimates of the long term specific runoff from Foster Lake it is possible to calculate the discharge from other adjacent catchments based on the assumption that they represent the same specific runoff. In May the flow in all streams and rivers in the Project were measured within a few days and in a steady discharge situation. The location of each measurement site is shown in Figure 7.1. The objective was to estimate the discharge distribution from the sub-catchments in the area and by this improve the knowledge about the quantitative contribution of water from Laksetværelv and Foster Lake to the recipient Lakseelv. G A F E D C Klimastation B Hydrometristation kilometer Figure 7-1 Catchment areas and locations for discharge measurements (red figures) Table 7-1 summarizes the estimated discharge of key watercourses in the Project area based on the measurement campaign in May. From the table it can be calculated that the discharge from Fostersø contribute with c. 20% of the water in Lakseelv at its outlet to the fjord. In addition a further 5% is added from catchment areas downstream Fostersø, so that 25% of the water in Lakseelv at the outlet comes from Laksetværelv. 22/32

23 A. Calculated B. Measured or B/A annual mean Calculated River Name Location Catchment* discharge ** May system area km2 l/s l/s A Lakse elv 100 meter us Laksetværelv B Laksetværelv outlet Foster Lake C Tributary river from north west D Laksetværelv us confluence from Månesø E Månesø river ds Månesø F Laksetværelv us delta G Lakseelv ds Laksetværelv Table 7-1 Characteristics of key water courses in the project area * Catchments area is derived from the 1: topographical maps. ** Based on specific runoff 42 l/s/km 2 and catchment area. 7.1 Conclusion of hydrological calculations The annual average discharge at the outlet of Fostersø is 0.15 m 3 /s or estimated as runoff 42 l/s/km 2 catchment area. On average Fostersø contribute annually with 20% of the water in Lakseelv. In addition further 5% is added from the catchment downstream, which in total is similar to 25% of water from Laksetværelv to Lakseelv. In winter situations with prolonged periods with frost, Fostersø is stopping feeding water to Laksetværelv. Intermediate thaw periods can cause sudden floods from Laksetværelv to Lakseelv. This was recorded in the measurement period - 23/32

24 8 REFERENCES Danish Meteorological Institute 2001.Technical Report The observed climate of Greenland /32

25 ANNEX 1 DISCHARGE DATA FROM FOSTERSØ m3/s Day JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Max * * * * Min * * * * Avg * * * * /32

26 m3/s Day JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Max * * Min * * Avg * * 26/32

27 LTEMP [C] ANNEX 2 MEASURED AIR TEMPERATURE AT KILLAVAAT ALIANNGUT jun aug okt nov Privat DDH : 1004 Killavaat Aliannguat, Minesite 1004 [ 1] [LTEMP] [EDT] [Øje] [MI] dec jan feb mar apr maj jun aug okt 27/32

28 V-Hast [m/s] ANNEX 3 MEASURED WIND SPEED AT KILLAVAAT ALIANNGUAT jun aug okt nov Privat DDH : 1004 Killavaat Aliannguat, Minesite 1004 [ 2] [V-Hast] [RAW] [Øje] [MI] dec jan feb mar apr maj jun aug okt 28/32

29 LFUGT [%] ANNEX 4 MEASURED RELATIVE HUMIDITY AT KILLAVAAT ALIANNGUAT jun aug okt Privat DDH : 1004 Killavaat Aliannguat, Minesite 1004 [ 1] [LFUGT] [RAW] [Øje] [MI] nov dec jan feb mar apr maj jun aug okt 29/32

30 NB [mm] ANNEX 5 MEASURED PRECIPITATION AT KILLAVAAT ALIANNGUAT ACCUMULATED DAILY TOTAL jun aug okt nov Privat DDH : 1004 Killavaat Aliannguat, Minesite 1004 [ 1] [NB] [DYN] [Sum] [DD] dec jan feb mar apr maj jun aug okt 30/32

31 ANNEX 6 MEASURED WIND DIRECTION DATA AT KILLAVAAT ALIANNGUAT HOURLY AVERAGE VALUES NORTH 20% 16% 12% 8% WEST 4% EAST WIND SPEED (m/s) SOUTH >= Calms: 9.68% 31/32

32 ANNEX 7 MEASURED WIND CLASS FREQUENCY AT KILLAVAAT ALIANNGUAT 45 Wind Class Frequency Distribution % Calms Wind Class (m/s) >= /32